A336458 Numbers k for which A065330(k) = A065330(sigma(k)).

1, 2, 3, 6, 28, 40, 84, 120, 135, 224, 270, 496, 672, 819, 1488, 1638, 3780, 8128, 10880, 24384, 30240, 32640, 32760, 66960, 167400, 174592, 406224, 523776, 1097280, 2178540, 3138345, 6276690, 6517665, 6656832, 8910720, 10480640, 13035330, 14705145, 17428320, 23569920, 29410290, 31441920, 33550336

Offset

1,2

Comments

Numbers k for which A065330(k) = A336457(k).

Question: Is this a subsequence of A336461?

Links

Table of n, a(n) for n=1..43.

Index entries for sequences where odd perfect numbers must occur, if they exist at all

Mathematica

Select[Range[10^5], SameQ @@ Map[Times @@ Map[#1^#2 & @@ # &, DeleteCases[ FactorInteger[#], _?(First@ # <= 3 &)]] &, {#, DivisorSigma[1, #]}] &, 97] (* Michael De Vlieger, Jul 24 2020 *)

Crossrefs

Cf. A000203, A065330, A336457.

Cf. A336461.

Subsequences: A000396, A005820.

Sequence in context: A228346 A269996 A336240 * A348867 A018318 A368209

Adjacent sequences: A336455 A336456 A336457 * A336459 A336460 A336461

Keyword

nonn

Author

Antti Karttunen, Jul 24 2020

Status

approved