A025707 Index of 5^n within sequence of numbers of form 5^i*6^j.

1, 2, 4, 7, 11, 16, 22, 29, 37, 46, 55, 65, 76, 88, 101, 115, 130, 146, 163, 181, 199, 218, 238, 259, 281, 304, 328, 353, 379, 406, 433, 461, 490, 520, 551, 583, 616, 650, 685, 721, 757, 794, 832, 871, 911, 952, 994, 1037, 1081, 1126, 1171, 1217, 1264, 1312, 1361

Offset: 0

Author

David W. Wilson

Keywords

• nonn
• easy

Comments

Positions of zeros in A025659. - R. J. Mathar, Jul 06 2025

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 0..10000

Programs

PARI

a(n)=my(N=1); n+1+sum(i=1, n, logint(N*=5, 6)); \\ Charles R Greathouse IV, Jan 11 2018

PARI

first(n)=my(s, N=1/5); vector(n+1, i, s+=logint(N*=5, 6)+1) \\ Charles R Greathouse IV, Jan 11 2018

Extensions

Offset corrected by Charles R Greathouse IV, Jan 11 2018