A180728 21^a(n) is smallest power of 21 beginning with n.

0, 1, 8, 2, 21, 15, 9, 6, 3, 28, 25, 22, 19, 16, 13, 10, 38, 7, 4, 32, 1, 29, 26, 85, 23, 82, 20, 79, 48, 17, 45, 14, 73, 42, 11, 39, 8, 67, 36, 5, 64, 33, 362, 2, 61, 30, 89, 58, 387, 27, 86, 55, 384, 24, 83, 52, 1191, 21, 80, 1219, 49, 288, 18, 77, 946, 46, 285, 15, 74, 1483, 43

Offset

1,3

Links

D. Mondot, Table of n, a(n) for n=1..32699

Mathematica

Module[{nn=1500, t21}, t21=Table[{n, IntegerDigits[21^n]}, {n, 0, nn}]; Table[SelectFirst[ t21, IntegerDigits[k]==Take[#[[2]], IntegerLength[k]]&], {k, 80}]][[;; , 1]]//Quiet (* Harvey P. Dale, May 14 2023 *)

Crossrefs

Cf. A180726, A180727, A180730

Sequence in context: A050096 A161593 A008866 * A308217 A248297 A340008

Adjacent sequences: A180725 A180726 A180727 * A180729 A180730 A180731

Keyword

base,nonn

Author

Daniel Mondot, Sep 18 2010

Status

approved