A171252 Least power of 2 to have at least n consecutive digits 'n' in its decimal expansion

0, 0, 43, 83, 192, 973, 2269, 972, 25263, 42485

Offset

0,3

Comments

As it stands, the definition makes only sense for (decimal digits) n=0,...,9. Replacing "decimal" by, e.g., base-(prime(n)), the sequence could be defined for all n. (However, e.g., base-(n+1) would not work, since in base 4 no power of 2 has a digit "3".)

Links

Table of n, a(n) for n=0..9.

Prog

(PARI) A171252(n)={my(p=10^n, t); n*=p\9; for(k=0, 1e9, t=2^k; until( n>t\=10, t%p==n & return(k)))}
for(d=0, 9, print(d" "A171252(d)))

Crossrefs

Cf. A131535 - A131543.

Sequence in context: A289730 A045238 A139982 * A119487 A180549 A247436

Adjacent sequences: A171249 A171250 A171251 * A171253 A171254 A171255

Keyword

base,fini,full,nonn

Author

M. F. Hasler, Dec 06 2009

Status

approved