A015906 -id:A015906 - cp's OEIS frontend

A015905 Numbers k such that k | 13^k + 13.

1, 2, 13, 14, 26, 182, 286, 2626, 2926, 8866, 10186, 57226, 62686, 118378, 185653, 187838, 284662, 396526, 689546, 792946, 927706, 1110214, 1140686, 1501526, 1943266, 2034406, 2402686, 2427706, 2759926, 3032926, 4450706, 6586426, 6849766, 7319026, 9357518

Offset: 1

Robert G. Wilson v

nonn

Giovanni Resta, Table of n, a(n) for n = 1..400

Cf. A006517, A015888, A015889, A015891, A015892, A015893, A015897, A015898, A015902, A015903, A015904, A015906.

Select[Range[10^6], Mod[13 + PowerMod[13, #, #], #] == 0 &] (* Giovanni Resta, Oct 21 2018 *)

Missing a(2) and a(33)-a(35) from Giovanni Resta, Oct 21 2018

A015908 Smallest odd k>n such that k | n^k + n, or 0 if n=2^m.

Original entry on oeis.org

1, 0, 0, 15, 0, 1565, 111, 35, 0, 123, 365, 671, 15, 185653, 259, 85, 0, 4369, 39, 247, 800005, 39, 55, 115, 1731, 85, 221, 135, 35, 105821, 51, 403, 0, 55, 1649, 1939, 3177, 3293, 95, 2283, 3845, 697, 357, 215, 143, 153, 667, 235, 435, 511, 485

Offset: 0

Robert G. Wilson v

nonn

Sean A. Irvine, Table of n, a(n) for n = 0..136

Cf. A015906 (without restriction on the parity of k).

fk[n_]:=Module[{k=n+1},If[EvenQ[k],k++];If[IntegerQ[Log[2,n]], k=0, While[ Mod[ n^k+n,k]!=0,k+=2]];k]; Array[fk,60,0] (* Harvey P. Dale, Mar 12 2019 *)

isp2(n) = (n==1) || (n==2) || (isprimepower(n, &p) && (p==2));
a(n) = {if (isp2(n), return (0)); my(k = if (n%2, n+2, n+1)); while(lift(Mod(n,k)^k + Mod(n,k)), k+=2); k;} \\ Michel Marcus, Dec 19 2018

Missing a(0)=1, a(1)=0 inserted and a(5) corrected by Sean A. Irvine, Dec 19 2018

cp's OEIS Frontend

A015905 Numbers k such that k | 13^k + 13.

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