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A063429 Smallest k such that 2^k has exactly n 3's in its decimal representation. 9
1, 5, 49, 25, 35, 109, 96, 128, 135, 169, 182, 156, 208, 302, 310, 277, 221, 300, 346, 498, 387, 502, 563, 507, 503, 611, 550, 585, 615, 681, 731, 817, 819, 835, 779, 860, 849, 840, 879, 997, 1016, 925, 1066, 1161, 1117, 1186, 1282, 1090, 1293, 1251, 1444 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
LINKS
MATHEMATICA
a = {}; Do[k = 1; While[ Count[ IntegerDigits[2^k], 3] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a
With[{dr=Table[{k, DigitCount[2^k, 10, 3]}, {k, 1500}]}, Table[SelectFirst[dr, #[[2]]==n&], {n, 0, 50}]][[;; , 1]] (* Harvey P. Dale, Jul 30 2023 *)
PROG
(PARI) a(n)={my(k=1); while(n<>#select(d->d==3, digits(2^k)), k++); k} \\ Harry J. Smith, Aug 20 2009, Andrew Howroyd, Jun 26 2018
CROSSREFS
Sequence in context: A346183 A224510 A333982 * A297856 A298091 A298053
KEYWORD
base,nonn
AUTHOR
Robert G. Wilson v, Aug 10 2001
EXTENSIONS
Name corrected by Jon E. Schoenfield, Jun 25 2018
STATUS
approved

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Last modified March 29 02:23 EDT 2024. Contains 371264 sequences. (Running on oeis4.)