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A180728
21^a(n) is smallest power of 21 beginning with n.
4
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
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
KEYWORD
base,nonn
AUTHOR
Daniel Mondot, Sep 18 2010
STATUS
approved