A274489 a(n) = floor(sinh(n) / n^2).

1, 0, 1, 1, 2, 5, 11, 23, 50, 110, 247, 565, 1308, 3067, 7264, 17355, 41790, 101327, 247205, 606456, 1495255, 3703422, 9210589, 22994029, 57603919, 144770421, 364916488, 922357821, 2337297441

Offset: 1

Author

Alessandro Polcini, Nov 10 2016

Keywords

• nonn
• easy
• hear

Comments

This sequence has some elements in common with A018112 (-> elements 1, 2, 5, 11, 23, 50, 110).

The sum of the reciprocals of a(n) (for n>=2) converges to 2.870623225848376377857...

Programs

Mathematica

Table[Floor[Sinh[n]/n^2],{n,30}] (* Harvey P. Dale, Nov 15 2018 *)

PARI

a(n)=localprec(19); localprec((n-log(2))\log(10)+9); sinh(n)\n^2 \\ Charles R Greathouse IV, Nov 10 2016

Formula

a(n) = floor(sinh(n)/(n^2)), for n >= 1.