A325979 - OEIS

A325979

Odd numbers k for which gcd(A325977(k), A325978(k)) is equal to abs(A325978(k)).

1, 3465, 72981, 78651, 80937, 152703, 199341, 201771, 241605, 253287, 492507, 631881, 880821, 933147, 985473, 1063755, 1209285, 1244133, 1292445, 1313235, 1327095, 1347885, 1360881, 1451835, 1521135, 1597365, 1620375, 1814373, 2015475, 2664585, 6058233, 6676371, 8186751, 11119761, 17496243, 18379935, 28695627

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OFFSET

1,2

COMMENTS

Provided that A325977(k) and A325978(k) are never zero for the same k, these are odd numbers k such that A325978(k) is not zero and divides A325977(k).

Of the first 65 terms, only a(5) = 80937 and a(51) = 86086881 are in A228058.

LINKS

Giovanni Resta, Table of n, a(n) for n = 1..281 (terms < 10^12; first 65 terms from Antti Karttunen)

Index entries for sequences where any odd perfect numbers must occur.

PROG

(PARI)

A034448(n) = { my(f=factorint(n)); prod(k=1, #f~, 1+(f[k, 1]^f[k, 2])); }; \\ After code in A034448

A034460(n) = (A034448(n) - n);

A048250(n) = factorback(apply(p -> p+1, factor(n)[, 1]));

A325313(n) = (A048250(n) - n);

A325977(n) = ((A034460(n)+A325313(n))/2);

A162296(n) = sumdiv(n, d, d*(1-issquarefree(d)));