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A063996
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Numbers k such that ud(k) = sopf(k)-1, where ud(k)=A034444(k) and sopf(k)=A008472(k).
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2
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3, 6, 9, 12, 18, 24, 27, 36, 48, 54, 72, 81, 96, 108, 144, 162, 192, 210, 216, 243, 288, 324, 384, 420, 432, 486, 576, 630, 648, 729, 768, 840, 864, 972, 1050, 1152, 1260, 1296, 1458, 1470, 1536, 1680, 1728, 1890, 1944, 2100, 2187, 2304, 2520, 2592, 2916
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OFFSET
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1,1
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LINKS
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PROG
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(PARI) sopf(n, s, fac, i)=fac=factor(n); for(i=1, matsize(fac)[1], s=s+fac[i, 1]); return(s); ud(n) = 2^omega(n); j=[]; for(n=1, 7000, if(ud(n)==sopf(n)-1, j=concat(j, n))); j
(PARI) sopf(n)= { local(f, s=0); f=factor(n); for(i=1, matsize(f)[1], s+=f[i, 1]); return(s) } { n=0; for (m=1, 10^9, if (2^omega(m)==sopf(m) - 1, write("b063996.txt", n++, " ", m); if (n==1000, break)) ) } \\ Harry J. Smith, Sep 05 2009
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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