A025660 -id:A025660 - cp's OEIS frontend

A025626 Numbers of form 6^i*7^j, with i, j >= 0.

1, 6, 7, 36, 42, 49, 216, 252, 294, 343, 1296, 1512, 1764, 2058, 2401, 7776, 9072, 10584, 12348, 14406, 16807, 46656, 54432, 63504, 74088, 86436, 100842, 117649, 279936, 326592, 381024, 444528, 518616, 605052, 705894, 823543, 1679616, 1959552

Offset: 1

David W. Wilson

Amiram Eldar, Table of n, a(n) for n = 1..10000

Cf. A025610, A025622, A025627, A025628, A025629.

Cf. A025619, A025631, A025632, A003591, A003594, A003595, A036566.

n = 10^6; Flatten[Table[6^i*7^j, {i, 0, Log[6, n]}, {j, 0, Log[7, n/6^i]}]] // Sort (* Amiram Eldar, Sep 25 2020 *)

Sum_{n>=1} 1/a(n) = (6*7)/((6-1)*(7-1)) = 7/5. - Amiram Eldar, Sep 25 2020
a(n) ~ exp(sqrt(2*log(6)*log(7)*n)) / sqrt(42). - Vaclav Kotesovec, Sep 25 2020
a(n) = 6^A025660(n) * 7^A025668(n). - R. J. Mathar, Jul 06 2025

A025724 Index of 7^n within sequence of numbers of form 6^i*7^j.

Original entry on oeis.org

1, 3, 6, 10, 15, 21, 28, 36, 45, 55, 66, 78, 92, 107, 123, 140, 158, 177, 197, 218, 240, 263, 287, 312, 339, 367, 396, 426, 457, 489, 522, 556, 591, 627, 664, 703, 743, 784, 826, 869, 913, 958, 1004, 1051, 1099, 1148, 1198, 1250, 1303, 1357, 1412, 1468, 1525, 1583

Offset: 1

David W. Wilson

nonn

Positions of zeros in A025660. - R. J. Mathar, Jul 06 2025

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A025626 Numbers of form 6^i*7^j, with i, j >= 0.

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A025724 Index of 7^n within sequence of numbers of form 6^i*7^j.

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