A260988 Numbers n such that sigma(n) = m*sigma(n+2) with some m > 1.

8505, 25500, 30360, 37740, 40740, 123795, 141480, 185460, 442365, 485400, 834435, 953568, 1055460, 1097820, 1108320, 1397220, 1953960, 2088480, 2208840, 2571744, 3050784, 3342816, 3544695, 3810456, 4314156, 4725660, 4867236, 5638776, 6318180, 6596340, 8428320, 8630832, 9347280, 9576336, 9908460, 10271580, 10992360, 11789925

Offset

1,1

Comments

Sequence A227304 is the union of A055574 and { a(n)+1 }.

Many but not all terms are multiples of 5.

Links

Table of n, a(n) for n=1..38.

Prog

(PARI) for(n=1, 2e9, sigma(n)%sigma(n+2)||sigma(n)==sigma(n+2)||print1(n", "))

Crossrefs

Cf. A000203, A055574, A067130, A058073.

Sequence in context: A253492 A253453 A348605 * A188214 A252810 A202986

Adjacent sequences: A260985 A260986 A260987 * A260989 A260990 A260991

Keyword

nonn

Author

M. F. Hasler, Aug 06 2015

Status

approved