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

Author

Paul Curtz, Sep 23 2008

Keywords

• nonn
• easy

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).

Crossrefs

Cf. A061037, A142590.

Programs

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 *)

Formula

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

Extensions

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

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