A113023 Number of terms in A095810 which have n digits.

5, 18, 90, 450, 2250, 11250, 56250, 281250, 1406250, 7031250, 35156250, 175781250

Offset

1,1

Comments

a(n+1)/a(n) = ~5.

Links

Table of n, a(n) for n=1..12.

Formula

t = sorted union of 2^k (mod 10^n), 0<k<=5^n; then count only those which have n digits.

Conjecture: a(n) = 18*5^(n-2) for n>1. - Mohammed Yaseen, Jul 19 2022

Mathematica

Do[t = Union[ Table[ PowerMod[2, i, 10^n], {i, 5^n}]]; Print[ Length[ Select[t, Floor[ Log[10, # ] + 1] == n &]]], {n, 10}] (* Robert G. Wilson v, Aug 27 2004 *)

Prog

(Python)
def a(n):
    b, m, t = 5**n+1, 10**n, 10**(n-1)
    return len(set(p for p in (pow(2, k, m) for k in range(b)) if p >= t))
print([a(n) for n in range(1, 10)]) # Michael S. Branicky, Jul 25 2022

Crossrefs

Cf. A095810, A113022.

Sequence in context: A185652 A009305 A097574 * A174082 A188329 A165962

Adjacent sequences: A113020 A113021 A113022 * A113024 A113025 A113026

Keyword

nonn,base,more

Author

Paul D. Hanna and Robert G. Wilson v, Aug 27 2004

Extensions

a(11)-a(12) from Michael S. Branicky, Jul 25 2022

Status

approved