A142599 Second trisection of A061037.

5, 2, 77, 35, 221, 20, 437, 143, 725, 56, 1085, 323, 1517, 110, 2021, 575, 2597, 182, 3245, 899, 3965, 272, 4757, 1295, 5621, 380, 6557, 1763, 7565, 506, 8645, 2303, 9797, 650, 11021, 2915, 12317, 812, 13685, 3599, 15125, 992, 16637, 4355, 18221, 1190, 19877, 5183, 21605, 1406, 23405

Offset

1,1

Comments

From Balmer spectrum of hydrogen. First trisection is A142590.

Links

G. C. Greubel, Table of n, a(n) for n = 1..10000

Index entries for linear recurrences with constant coefficients, signature (0,0,0,3,0,0,0,-3,0,0,0,1).

Formula

Sum_{n>=1} 1/a(n) = 5*Pi/(24*sqrt(3)) + 1/2. - Amiram Eldar, Sep 11 2022

Mathematica

A061037[n_] := Numerator[(n-2)*(n+2)/(4*n^2)]; Table[A061037[n], {n, 1, 300}][[3 ;;  ;; 3]] (* G. C. Greubel, Sep 19 2018 *)

Crossrefs

Cf. A061037, A142590.

Sequence in context: A208927 A099612 A233044 * A266461 A068566 A347426

Adjacent sequences: A142596 A142597 A142598 * A142600 A142601 A142602

Keyword

nonn,easy

Author

Paul Curtz, Sep 23 2008

Extensions

Edited by N. J. A. Sloane, Sep 27 2008

Terms a(18) onward added by G. C. Greubel, Sep 19 2018

Status

approved