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

1,3

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

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

Example

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

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 *)

Prog

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

Crossrefs

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

Sequence in context: A068578 A203812 A135667 * A113769 A056865 A097602

Adjacent sequences: A047891 A047892 A047893 * A047895 A047896 A047897

Keyword

nonn,base

Author

Labos Elemer

Extensions

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

Status

approved