A365456 - OEIS

A365456

a(n) = A156552(2*n) / gcd(sigma(n), A156552(2*n)).

1, 1, 5, 1, 3, 11, 17, 1, 1, 19, 11, 23, 65, 35, 7, 1, 43, 9, 257, 13, 37, 67, 171, 47, 25, 131, 29, 71, 205, 43, 2049, 1, 23, 259, 41, 55, 4097, 103, 19, 79, 2731, 25, 16385, 45, 15, 1027, 10923, 95, 49, 17, 29, 263, 65537, 59, 73, 143, 517, 2051, 43691, 29, 262145, 4099, 77, 1, 137, 139, 524289, 173, 343, 83

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OFFSET

1,3

COMMENTS

Denominator of ratio sigma(n) / A156552(2*n).

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..8192

Index entries for sequences computed from indices in prime factorization

Index entries for sequences related to sigma(n)

FORMULA

a(n) = A156552(2*n) / A365454(n).

PROG

(PARI)

A156552(n) = {my(f = factor(n), p, p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res}; \\ From A156552

A365456(n) = { my(u=A156552(2*n)); (u/gcd(u, sigma(n))); };

CROSSREFS

Cf. A000203, A156552, A365454, A365455 (numerators), A365457.

Sequence in context: A176321 A248130 A365457 * A134894 A143700 A036790

Adjacent sequences: A365453 A365454 A365455 * A365457 A365458 A365459

KEYWORD

nonn,frac

AUTHOR

Antti Karttunen, Sep 10 2023

STATUS

approved