|
Search: id:A058885
|
|
|
| A058885 |
|
a(n) = smallest k such that k! ends in 2^n, not counting the trailing zeros. |
|
+0
2
|
|
| 0, 2, 4, 9, 12, 8, 20, 33, 159, 43, 49, 348, 60, 91, 8134, 1964, 1392, 735, 34060, 9030, 14052, 39306, 16906, 29338, 53711, 356449, 88137, 543041, 1435398, 1000154, 5037980, 2245246, 499245, 6240345, 2989574, 34190394, 11257817, 146038526
(list; graph; listen)
|
|
|
OFFSET
|
0,2
|
|
|
EXAMPLE
|
a(4) = 12 because 12! = 479001600. When you delete the trailing zeros, you have 4790016 which ends in 16 = 2^4.
|
|
MATHEMATICA
|
f[n_] := Block[{a = 2^n, k = 1, len = 10^Floor[ Log[10, 2^n] + 1], p = 1}, While[ Mod[p, len] != a, p = k*p; While[ Mod[p, 10] == 0, p /= 10]; p = Mod[p, 100*len]; k++ ]; k - 1]; lst = {}; Do[ AppendTo[ lst, f@n], {n, 0, 37}]
|
|
CROSSREFS
|
Cf. A059449.
Sequence in context: A093859 A115905 A096134 this_sequence A022428 A096186 A088901
Adjacent sequences: A058882 A058883 A058884 this_sequence A058886 A058887 A058888
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 07 2001
|
|
EXTENSIONS
|
a(15) corrected, a(18) through a(37) and better definition from Jon E. Schoenfield (jonscho@hiwaay.net) Sep 02 2009.
|
|
|
Search completed in 0.002 seconds
|
