

A031146


Exponent of the least power of 2 having exactly n zeros in its decimal representation.


16



0, 10, 42, 43, 79, 88, 100, 102, 189, 198, 242, 250, 252, 263, 305, 262, 370, 306, 368, 383, 447, 464, 496, 672, 466, 557, 630, 629, 628, 654, 657, 746, 771, 798, 908, 913, 917, 906, 905, 1012, 1113, 988, 1020, 989, 1044, 1114, 1120, 1118, 1221, 1218, 1255
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OFFSET

0,2


LINKS

T. D. Noe, Table of n, a(n) for n = 0..1000


EXAMPLE

a(3) = 43 since 2^m contains 3 0's for m starting with 43 (2^43 = 8796093022208) and followed by 53, 61, 69, 70, 83, 87, 89, 90, 93, ...


MATHEMATICA

a = {}; Do[k = 0; While[ Count[ IntegerDigits[2^k], 0] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a (* Robert G. Wilson v, Jun 12 2004 *)
nn = 100; t = Table[0, {nn}]; found = 0; k = 0; While[found < nn, k++; cnt = Count[IntegerDigits[2^k], 0]; If[cnt <= nn && t[[cnt]] == 0, t[[cnt]] = k; found++]]; t = Join[{0}, t] (* T. D. Noe, Mar 14 2012 *)


PROG

(PARI) A031146(n)=for(k=0, oo, #select(d>!d, digits(2^k))==n&&return(k)) \\ M. F. Hasler, Jun 15 2018


CROSSREFS

Cf. A000079, A007377, A031147, A006889.
Cf. A063555 (analog for 3^k), A063575 (for 4^k), A063585 (for 5^k), A063596 (for 6^k), A063606 (for 7^k), A063616 (for 8^k), A063626 (for 9^k).
Sequence in context: A113683 A060994 A086544 * A328536 A163815 A108678
Adjacent sequences: A031143 A031144 A031145 * A031147 A031148 A031149


KEYWORD

base,nonn


AUTHOR

N. J. A. Sloane


EXTENSIONS

More terms from Erich Friedman
Definition clarified by Joerg Arndt, Sep 27 2016


STATUS

approved



