A383692 a(n) = round(Chi(n)) where Chi(x) is the cosh integral function.

1, 2, 5, 10, 20, 43, 96, 220, 519, 1246, 3036, 7480, 18599, 46596, 117478, 297780, 758319, 1938952, 4975454, 12807826, 33063593, 85572336, 221983185, 577057696, 1502975453, 3921470496, 10248248560, 26822559296, 70299597879, 184486604704, 484727787984

Offset

1,2

Comments

This sequence is almost the same as A383542, except at n = 0, where Chi(0) is undefined, and at n = 2, where Shi(2) = 2.50156... rounds to 3, while Chi(2) = 2.45266... rounds to 2.

Links

Table of n, a(n) for n=1..31.

Formula

a(n) ~ exp(n)/(2*n). - Vaclav Kotesovec, Sep 30 2025

Mathematica

a[n_]:=Round[CoshIntegral[n]]; Array[a, 31]

Crossrefs

Cf. A383542.

Sequence in context: A129847 A330456 A352120 * A176692 A212951 A051109

Adjacent sequences: A383689 A383690 A383691 * A383693 A383694 A383695

Keyword

nonn

Author

Kritsada Moomuang, May 05 2025

Status

approved