A348689 a(n) = sigma(n) + sigma(n+1) - sigma(n+2), where sigma is the sum of divisors.

0, 0, 5, 1, 10, 5, 10, 10, 19, 2, 26, 18, 14, 17, 37, 10, 37, 17, 30, 38, 44, 0, 53, 49, 33, 26, 66, 14, 70, 41, 47, 57, 54, 11, 101, 69, 42, 26, 104, 36, 94, 56, 50, 90, 102, -4, 115, 88, 78, 67, 116, 32, 102, 72, 112, 110, 110, -18, 166, 134, 54, 73, 147, 67, 160, 86, 98, 78, 168, 21

Offset

1,3

Links

Michel Marcus, Table of n, a(n) for n = 1..10000

Mathematica

Array[#+#2-#3&@@DivisorSigma[1, {#, #+1, #+2}]&, 100] (* Giorgos Kalogeropoulos, Oct 29 2021 *)

Prog

(PARI) a(n) = sigma(n)+sigma(n+1) - sigma(n+2);

Crossrefs

Cf. A000203, A104149, A348688.

Sequence in context: A333448 A050308 A063475 * A329752 A363969 A135855

Adjacent sequences: A348686 A348687 A348688 * A348690 A348691 A348692

Keyword

sign

Author

Michel Marcus, Oct 29 2021

Status

approved