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A257146
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Primitive non-solvable numbers: elements of A056866 not divisible by any earlier term.
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4
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60, 168, 1092, 2448, 5616, 6072, 25308, 29120, 32736, 39732, 51888, 74412, 150348, 194472, 285852, 546312, 612468, 1285608, 1934868, 2097024, 2165292, 2588772, 3594432, 3822588, 5848428, 6324552, 7174332, 8487168, 9095592, 10626828, 11332452, 12576732, 14467068, 15331992, 15927348
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OFFSET
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1,1
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COMMENTS
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A number is solvable if and only if it is a positive multiple of a member of this sequence.
There is 1 member of this sequence up to 10^2, 2 up to 10^3, 6 up to 10^4, 12 up to 10^5, 17 up to 10^6, 29 up to 10^7, 49 up to 10^8, 89 up to 10^9, 169 up to 10^10, 321 up to 10^11, 616 up to 10^12, 1188 up to 10^13, 2351 up to 10^14, 4679 up to 10^15, 9350 up to 10^16, 18866 up to 10^17, 38157 up to 10^18, 77534 up to 10^19, 158048 up to 10^20, 323358 up to 10^21, 663159 up to 10^22, and 1363304 up to 10^23. - Charles R Greathouse IV, Sep 16 2015
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LINKS
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FORMULA
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PROG
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(PARI) list(lim)={
my(v=List(), t);
forprime(p=2, ,
t=(4^p-1)<<p;
if(t>lim, break);
listput(v, t)
);
forprime(p=3, ,
t=3^p*(9^p-1)/2;
if(t>lim, break);
listput(v, t)
);
forprime(p=7, ,
t=p*(p^2-1)/2;
if(t>lim, break);
listput(v, t)
);
forprime(p=3, ,
t=4^p*(4^p+1)*(2^p-1);
if(t>lim, break);
listput(v, t)
);
if(lim>=5616, listput(v, 5616));
v=Set(v);
for(i=1, #v,
if(v[i]==60 && i>1, next); \\ see below
for(j=i+1, #v,
if(v[j]%v[i]==0, v[j]=60) \\ delete values by setting to v[1]
)
);
Set(v); \\ remove duplicates to combine all 60s
}
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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