A332456 Numbers k such that sigma(sigma(k)) is congruent to 6 modulo 8.

9, 67, 163, 193, 201, 202, 271, 338, 469, 489, 505, 547, 579, 606, 670, 673, 729, 813, 982, 1087, 1111, 1123, 1139, 1141, 1153, 1201, 1223, 1351, 1354, 1407, 1414, 1423, 1474, 1515, 1543, 1601, 1630, 1641, 1642, 1791, 1873, 1897, 1930, 1966, 2010, 2017, 2019, 2077, 2083, 2088, 2323, 2326, 2371, 2447, 2455, 2467, 2503

Offset: 1

Author

Antti Karttunen, Feb 15 2020

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..10000
• Index entries for sequences related to sigma(n)

Crossrefs

Cf. A000203, A051027, A332226, A332457, A332458.

Programs

PARI

isA332456(n) = (6==(sigma(sigma(n))%8));