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A018866 7^a(n) is smallest power of 7 beginning with n. 2
0, 4, 3, 2, 8, 14, 1, 7, 13, 45, 6, 38, 12, 57, 31, 5, 50, 37, 11, 69, 43, 30, 17, 4, 49, 36, 23, 10, 68, 55, 42, 29, 16, 3, 61, 48, 35, 106, 22, 9, 67, 138, 54, 41, 28, 99, 15, 228, 2, 60, 131, 47, 260, 34, 21, 92, 8, 150, 66, 137, 53, 195, 40, 182, 27, 98, 14, 85, 298, 72, 285 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

MATHEMATICA

With[{s=7^Range[0, 500]}, Flatten[Table[Position[s, _?(IntegerDigits[n] ==  Take[IntegerDigits[#], IntegerLength[n]]&), 1, 1], {n, 80}]]]-1//Quiet (* Harvey P. Dale, Feb 22 2018 *)

CROSSREFS

Sequence in context: A022295 A258415 A132668 * A021235 A273991 A292828

Adjacent sequences:  A018863 A018864 A018865 * A018867 A018868 A018869

KEYWORD

nonn,base

AUTHOR

David W. Wilson

STATUS

approved

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Last modified February 28 06:55 EST 2020. Contains 332321 sequences. (Running on oeis4.)