|
Search: id:A139126
|
|
|
| A139126 |
|
Least k such that the last n decimal digits of 2^k are all powers of 2. |
|
+0
1
|
|
| 0, 7, 7, 18, 19, 90, 91, 271, 1751, 18807, 56589, 56589, 56589, 56589, 899791, 899791, 2814790, 7635171, 7635171, 39727671, 99530619, 233093807, 233093807, 233093807, 233093807
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
Does k exist for all n? This sequence is inspired by A130693, which lists all known powers of 2 whose digits are all powers of 2 (that is, 1, 2, 4, or 8).
|
|
EXAMPLE
|
2^19=524288 is the least power of 2 ending with 5 digits that are powers of 2.
|
|
MATHEMATICA
|
k=1; Join[{0}, Table[k--; pwr=PowerMod[2, k, 10^n]; While[k++; pwr=Mod[2*pwr, 10^n]; d=Union[IntegerDigits[pwr, 10, n]]; Intersection[d, {3, 5, 6, 7, 9, 0}]!={}]; k, {n, 2, 10}]]
|
|
CROSSREFS
|
Sequence in context: A022090 A120682 A100635 this_sequence A070919 A070847 A053416
Adjacent sequences: A139123 A139124 A139125 this_sequence A139127 A139128 A139129
|
|
KEYWORD
|
base,nonn
|
|
AUTHOR
|
T. D. Noe (noe(AT)sspectra.com), Apr 08 2008
|
|
|
Search completed in 0.002 seconds
|
