A351440 Numbers k for which A003958(sigma(k)) + A064989(sigma(k)) is equal to A003958(k) + A064989(k).

1, 6, 28, 496, 8128, 30240, 32760, 240408, 2178540, 6828720, 13042080, 23569920, 33550336, 42402048, 45532800, 142990848, 1379454720

Offset

1,2

Links

Table of n, a(n) for n=1..17.

Index entries for sequences where odd perfect numbers must occur, if they exist at all

Index entries for sequences related to sigma(n)

Prog

(PARI)
A003958(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1]--); factorback(f); };
A064989(n) = { my(f = factor(n>>valuation(n, 2))); for(i=1, #f~, f[i, 1] = precprime(f[i, 1]-1)); factorback(f); };
isA351440(n) = { my(s=sigma(n)); ((A003958(s)+A064989(s)) == (A003958(n)+A064989(n))); };

Crossrefs

Cf. A000203, A003958, A064989, A351442.

Subsequence of A351446.

Subsequences: A000396, A336702.

Sequence in context: A174633 A345004 A370789 * A325637 A336702 A325654

Adjacent sequences: A351437 A351438 A351439 * A351441 A351442 A351443

Keyword

nonn,more

Author

Antti Karttunen, Feb 12 2022

Status

approved