|
|
A022334
|
|
Index of 5^n within sequence of numbers of form 2^i * 5^j.
|
|
2
|
|
|
1, 4, 9, 16, 26, 38, 52, 69, 88, 109, 133, 159, 187, 218, 251, 286, 324, 364, 406, 451, 498, 547, 599, 653, 709, 768, 829, 892, 958, 1026, 1096, 1168, 1243, 1320, 1399, 1481, 1565, 1651, 1740, 1831, 1924, 2020, 2118, 2218, 2321, 2426, 2533, 2643, 2755, 2869, 2986
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,2
|
|
COMMENTS
|
|
|
LINKS
|
|
|
FORMULA
|
a(n) = Sum_{i=0..n} 1 + floor(log(5^i)/log(2)). - Michel Marcus, Oct 02 2013
|
|
MATHEMATICA
|
Table[1 + Sum[Ceiling[j*Log[2, 5]], {j, i}], {i, 0, 50}] (* Michael De Vlieger, Feb 08 2023 *)
|
|
PROG
|
(PARI) a(n) = sum(i=0, n, 1 + floor(log(5^i)/log(2))); \\ Michel Marcus, Oct 02 2013
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|