A303772 Inverse of A303771.

0, 1, 3, 5, 9, 2, 17, 6, 33, 10, 65, 4, 129, 18, 12, 257, 513, 34, 1025, 14, 20, 66, 2049, 7, 4097, 130, 36, 22, 8193, 11, 16385, 258, 68, 514, 26, 38, 32769, 1026, 132, 15, 65537, 19, 131073, 70, 42, 2050, 262145, 260

Offset

1,3

Links

Table of n, a(n) for n=1..48.

Index entries for sequences that are permutations of the natural numbers

Formula

a(n) = A303768(A052331(n)).

Prog

(PARI)
default(parisizemax, 2^31);
up_to_e = 18;
up_to = (2 + 2^up_to_e);
v050376 = vector(2+up_to_e);
A050376(n) = v050376[n];
ispow2(n) = (n && !bitand(n, n-1));
i = 0; for(n=1, oo, if(ispow2(isprimepower(n)), i++; v050376[i] = n); if(i == 2+up_to_e, break));
A052330(n) = { my(p=1, i=1); while(n>0, if(n%2, p *= A050376(i)); i++; n >>= 1); (p); };
A053669(n) = forprime(p=2, , if (n % p, return(p))); \\ From A053669
v303760 = vector(up_to);
m_inverses = Map();
prev=1; for(n=1, up_to, fordiv(prev, d, if(!mapisdefined(m_inverses, d), v303760[n] = d; mapput(m_inverses, d, n); break)); if(!v303760[n], apu = prev; while(mapisdefined(m_inverses, try = prev*A053669(apu)), apu *= A053669(apu)); v303760[n] = try; mapput(m_inverses, try, n)); prev = v303760[n]);
A303760(n) = v303760[n+1];
A048675(n) = { my(f = factor(n)); sum(k=1, #f~, f[k, 2]*2^primepi(f[k, 1]))/2; };
A303771(n) = A052330(A048675(A303760(n)));
m303772 = Map();
for(n=0, up_to-1, mapput(m303772, A303771(n), n));
A303772(n) = mapget(m303772, n);

Crossrefs

Cf. A052331, A303768.

Sequence in context: A225594 A210946 A319984 * A200510 A138055 A236556

Adjacent sequences: A303769 A303770 A303771 * A303773 A303774 A303775

Keyword

nonn,more

Author

Antti Karttunen, May 02 2018

Status

approved