A387404 Numbers of the form 12*k + 1 that satisfy Euler's condition for odd perfect numbers (A228058).

325, 637, 925, 1525, 1573, 1813, 1825, 2425, 2725, 2989, 3577, 3757, 3925, 4477, 4525, 4693, 4753, 4825, 5341, 5725, 6025, 6253, 6877, 6925, 7381, 7693, 7825, 8125, 8425, 8725, 8833, 8869, 9325, 9457, 9925, 10225, 10309, 10525, 10693, 10825, 10933, 11221, 11425, 11737, 11809, 12337, 12493, 13189, 13357, 13525, 13573

Offset

1,1

Links

Antti Karttunen, Table of n, a(n) for n = 1..10000

Mathematica

nn = 51; n = 1; t = {}; While[Length[t] < nn, n = n + 2; {p, e} = Transpose[FactorInteger[n]]; od = Select[e, OddQ]; If[Length[e] > 1 && Length[od] == 1 && Mod[od[[1]], 4] == 1 && Mod[p[[Position[e, od[[1]]][[1, 1]]]], 4] == 1&&Mod[n, 12]==1, AppendTo[t, n]]]; t (* James C. McMahon, Aug 29 2025 *)

Prog

(PARI) is_A387404(n) = if(1!=(n%12) || (omega(n)<2), 0, my(f=factor(n), y=0); for(i=1, #f~, if(1==(f[i, 2]%4), if((1==y)||(1!=(f[i, 1]%4)), return(0), y=1), if(f[i, 2]%2, return(0)))); (y));

Crossrefs

Intersection of A017533 and A228058.

Sequence in context: A025304 A351801 A160580 * A158272 A383518 A183645

Adjacent sequences: A387401 A387402 A387403 * A387405 A387406 A387407

Keyword

nonn

Author

Antti Karttunen, Aug 29 2025

Status

approved