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A025713
Index of 6^n within the sequence of the numbers of the form 3^i*6^j.
1
1, 3, 7, 12, 19, 28, 38, 50, 64, 79, 96, 114, 134, 156, 179, 204, 231, 259, 289, 320, 353, 388, 424, 462, 502, 543, 586, 631, 677, 725, 774, 825, 878, 932, 988, 1046, 1105, 1166, 1228, 1292, 1358, 1425, 1494, 1565, 1637, 1711, 1787, 1864, 1943, 2023, 2105, 2189
OFFSET
0,2
COMMENTS
Positions of zeros in A025641. - R. J. Mathar, Jul 06 2025
LINKS
FORMULA
From Amiram Eldar, Nov 13 2025: (Start)
A025614(a(n)) = 6^n.
a(n) = 1 + Sum_{k=0..n} ceiling(k * c), where c = log_3(6) (A153459).
a(n) ~ c * n^2 / 2, where c is defined above. (End)
MATHEMATICA
Accumulate[Table[Ceiling[n * Log[3, 6]], {n, 0, 60}]] + 1 (* Amiram Eldar, Nov 13 2025 *)
CROSSREFS
KEYWORD
nonn,easy
EXTENSIONS
Offset corrected by Amiram Eldar, Nov 13 2025
STATUS
approved