A340713 Numbers k such that sigma(k+1) = 4 * sigma(k).

37033919, 141162839, 264995639, 596672999, 606523679, 630777839, 791656319, 920424119, 1060332839, 1379454719, 1954690919, 3799661039, 4024838999, 4633959959, 5393988599, 5935994063, 8831231639, 9866482079, 11237657759, 11273710139, 12266364599, 14440498379, 14952625379

Offset: 1

Author

Seiichi Manyama, Jan 17 2021

Keywords

• nonn

Links

• Seiichi Manyama, Table of n, a(n) for n = 1..40 (using A058072 data)

Crossrefs

Cf. A000203, A002961, A058072, A067081, A077087, A340715.

Programs

PARI

isok(k) = sigma(k+1) == 4*sigma(k); \\ Michel Marcus, Jan 18 2021

Extensions

a(10)-a(23) from Seiichi Manyama using A058072 data, Jan 17 2021