A043296 Sum of digits of denominator of Bernoulli number B(2n).

6, 3, 6, 3, 12, 12, 6, 6, 24, 6, 12, 12, 6, 15, 12, 6, 6, 30, 6, 12, 15, 15, 12, 15, 12, 15, 24, 15, 12, 42, 6, 6, 21, 3, 24, 21, 6, 3, 15, 6, 21, 15, 6, 12, 21, 6, 6, 24, 6, 12, 15, 15, 12, 30, 15, 24, 6, 15, 6, 39, 6, 3, 42, 6, 24, 24, 6, 6, 30, 33, 6, 42, 6, 15, 21, 3, 12, 42, 6, 6

Offset

1,1

Links

Table of n, a(n) for n=1..80.

Formula

a(n) = A007953(A002445(n)). - Michel Marcus, Feb 16 2021

Example

Denominator(B(2*9))=798 and 7+9+8=24 hence a(9)=24.

Mathematica

Total[IntegerDigits[#]]&/@Denominator[BernoulliB[2*Range[80]]] (* Harvey P. Dale, Jul 02 2017 *)

Prog

(PARI) a(n) = sumdigits(denominator(bernfrac(2*n))); \\ Michel Marcus, Feb 16 2021
(Python)
from sympy import bernoulli
def a(n): return sum(map(int, str(bernoulli(2*n).denominator())))
print([a(n) for n in range(1, 81)]) # Michael S. Branicky, Jun 03 2021

Crossrefs

Cf. A002445, A007953, A043295.

Sequence in context: A194625 A165065 A069938 * A199186 A176715 A229522

Adjacent sequences: A043293 A043294 A043295 * A043297 A043298 A043299

Keyword

base,easy,nonn

Author

Benoit Cloitre, Mar 24 2002

Status

approved