A053379 a(n) contains n digits '7' or '8' and is divisible by 2^n.

8, 88, 888, 7888, 77888, 877888, 7877888, 87877888, 787877888, 8787877888, 88787877888, 888787877888, 8888787877888, 88888787877888, 788888787877888, 8788888787877888, 88788888787877888, 888788888787877888, 7888788888787877888, 87888788888787877888

Offset

1,1

Links

Ray Chandler, Table of n, a(n) for n = 1..1000

Formula

a(n)=a(n-1)+10^(n-1)*(8-[a(n-1)/2^(n-1) mod 2]) i.e. a(n) ends with a(n-1); if (n-1)-th term is divisible by 2^n then n-th term begins with an 8, if not then n-th term begins with a 7.

Prog

(PARI) A053379_first(n, t=0)=vector(n, k, t+=(8-(t%2^k>0))*10^(k-1)) \\ M. F. Hasler, Feb 02 2026

Crossrefs

Cf. A023414, A050621, A050622, A035014.

Sequence in context: A053377 A053378 A062185 * A002282 A112907 A053380

Adjacent sequences: A053376 A053377 A053378 * A053380 A053381 A053382

Keyword

base,nonn

Author

Henry Bottomley, Mar 06 2000

Status

approved