A067825 Even values of k such that sigma(k + 1) > sigma(k).

2, 62, 74, 134, 146, 194, 254, 314, 398, 404, 458, 482, 494, 524, 554, 566, 614, 626, 662, 674, 692, 734, 758, 764, 794, 818, 854, 914, 944, 974, 998, 1034, 1094, 1124, 1154, 1214, 1238, 1286, 1322, 1394, 1454, 1514, 1538, 1574, 1646, 1658, 1682, 1754

Offset: 1

Author

Benoit Cloitre, Feb 08 2002

Keywords

• nonn

Comments

Most terms are == 2 (mod 6), first term == 4 (mod 6) is a(365) = 13474. - Zak Seidov, Apr 18 2013

First term == 0 (mod 6) may be 296527606374. - Jianing Song, Apr 01 2018

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..2000 from Zak Seidov)

Crossrefs

Cf. A000203 (sigma), A053224.

Programs

GAP

Filtered([2,4..2000],n->Sigma(n+1)>Sigma(n)); # Muniru A Asiru, Apr 03 2018

Mathematica

Select[Range[2, 2000, 2], DivisorSigma[1, #] < DivisorSigma[1, # + 1] &] (* Zak Seidov, Apr 18 2013 *)

PARI

is(n) = !(n%2) && sigma(n + 1) > sigma(n); \\ Amiram Eldar, Apr 23 2024