OFFSET
1,2
COMMENTS
Also, numbers n such that n divides s(n), where s(1)=1, s(k)=s(k-1)+k*22^(k-1) (cf. A014940).
LINKS
Max Alekseyev, Table of n, a(n) for n = 1..69065
MATHEMATICA
nxt[{n_, s_}]:={n+1, s+(n+1)*22^n}; Transpose[Select[NestList[nxt, {1, 1}, 7500], Divisible[ Last[#], First[#]]&]][[1]] (* Harvey P. Dale, Jan 27 2015 *)
CROSSREFS
Integers n such that n divides b^n - 1: A067945 (b=3), A014945 (b=4), A067946 (b=5), A014946 (b=6), A067947 (b=7), A014949 (b=8), A068382 (b=9), A014950 (b=10), A068383 (b=11), A014951 (b=12), A116621 (b=13), A014956 (b=14), A177805 (b=15), A014957 (b=16), A177807 (b=17), A128358 (b=18), A125000 (b=19), A128360 (b=20), A014960 (b=24).
KEYWORD
nonn
AUTHOR
EXTENSIONS
Edited by Max Alekseyev, Nov 16 2019
STATUS
approved