A018866 -id:A018866 - cp's OEIS frontend

A018865 Smallest power of 7 that begins with n.

1, 2401, 343, 49, 5764801, 678223072849, 7, 823543, 96889010407, 107006904423598033356356300384937784807, 117649, 129934811447123020117172145698449, 13841287201, 1481113296616977741464105532513750734030421355207

Offset: 1

David W. Wilson

Seiichi Manyama, Table of n, a(n) for n = 1..237

Cf. A018802 (k=2), A018857 (k=3), A018859 (k=4), A018861 (k=5), A018863 (k=6), this sequence (k=7), A018867 (k=8), A018869 (k=9).

a(n) = 7^A018866(n). - Seiichi Manyama, Jan 30 2017

a(7^n) = 7^n for n >= 0. - Seiichi Manyama, Jan 30 2017

One more term (a(14)) from Harvey P. Dale, Mar 04 2014

A018862 5^a(n) is smallest power of 5 beginning with n.

Original entry on oeis.org

0, 2, 5, 11, 1, 4, 7, 50, 10, 63, 23, 3, 56, 26, 6, 69, 49, 29, 9, 82, 62, 42, 22, 12, 2, 75, 55, 45, 25, 15, 5, 88, 68, 58, 48, 38, 28, 18, 8, 91, 81, 71, 61, 51, 41, 31, 21, 11, 104, 94, 84, 74, 167, 64, 54, 44, 137, 34, 24, 117, 14, 4, 97, 87, 180, 77, 67, 160, 57, 150, 47, 37, 130

Offset: 1

David W. Wilson

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

Cf. A018861.

Cf. A018858, A018860, A018864, A018866, A018868, A062525, A062526.

a(n) = my(k=0, ss=Str(n)); while(strsplit(Str(5^k), ss)[1] != "", k++); k; \\ Michel Marcus, Aug 19 2025

cp's OEIS Frontend

A018865 Smallest power of 7 that begins with n.

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