A025728 Index of 8^n within sequence of numbers of form 3^i*8^j (A025615).

1, 3, 7, 13, 21, 31, 43, 57, 73, 91, 110, 131, 154, 179, 206, 235, 266, 299, 334, 370, 408, 448, 490, 534, 580, 628, 678, 730, 783, 838, 895, 954, 1015, 1078, 1143, 1210, 1279, 1350, 1422, 1496, 1572, 1650, 1730, 1812, 1896, 1982, 2070, 2159, 2250, 2343, 2438

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Comments

Positions of zeros in A025643. - R. J. Mathar, Jul 06 2025

Crossrefs

Cf. A025615, A025699 (similar for 3^n).

Formula

A025615(a(n)) = 8^(n-1). - Bernard Schott, Dec 27 2021