A047894 Number of digits of A000182(n).

1, 1, 2, 3, 4, 6, 8, 10, 12, 14, 16, 19, 21, 23, 26, 28, 31, 34, 36, 39, 42, 45, 48, 51, 54, 57, 60, 63, 66, 69, 72, 76, 79, 82, 85, 89, 92, 95, 99, 102, 105, 109, 112, 116, 119, 123, 126, 130, 134, 137, 141, 144, 148, 152, 155, 159, 163, 167, 170, 174, 178, 182, 185

Offset: 1

Author

Labos Elemer

Keywords

• nonn
• base

Examples

			a(7) = 8 since the 7th tangential number is 22368256, which has 8 decimal digits.
		

References

• J. Peters and J. Stein, Mathematische Tafeln. Revised Russian Edition, 1968, Moscow.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000182, A055642, A000384, A034972, A034971, A047893.

Programs

Mathematica

a[n_] := IntegerLength[(2^(2*n)*(2^(2*n) - 1)*Abs[BernoulliB[2*n]])/(2*n)]; Array[a, 100] (* Amiram Eldar, Mar 17 2025 after Stan Wagon at A000182 *)

Python

from sympy import bernoulli
def A047894(n): return len(str(abs(((2-(2<<(m:=n<<1)))*bernoulli(m)<Chai Wah Wu, Apr 14 2023

Formula

a(n) = floor(log_10(A000182(n))) + 1. - Franklin T. Adams-Watters, Mar 29 2014

a(n) = A055642(A000182(n)). - Michel Marcus, Apr 15 2023

Extensions

a(1) corrected by Chai Wah Wu, Apr 14 2023