A181763 a(n) = A061037(n)^2.

0, 25, 9, 441, 4, 2025, 225, 5929, 36, 13689, 1225, 27225, 144, 48841, 3969, 81225, 400, 127449, 9801, 190969, 900, 275625, 20449, 385641, 1764, 525625, 38025, 700569, 3136, 915849, 65025, 1177225, 5184, 1490841, 104329, 1863225, 8100

Offset: 2

Author

Paul Curtz, Nov 14 2010

Keywords

• nonn
• easy

Comments

A061038(n)/a(n+2) for n >= 2 gives the reduced fractions 1/9, 4/49, 4, 4/81, 1/25, 4/121, 16/9, 4/169, ...

Links

• G. C. Greubel, Table of n, a(n) for n = 2..1000

Crossrefs

Cf. A061037, A061038.

Programs

Magma

A061037:=func< n | Numerator(1/4-1/n^2) >; A181763:=func< n | A061037(n)^2 >; [ A181763(n): n in [2..50] ]; // Klaus Brockhaus, Jan 09 2011

Mathematica

A061037[n_] := Numerator[(n - 2)*(n + 2)/(4 n^2)]; Table[A061037[n]^2, {n, 2, 100}] (* G. C. Greubel, Sep 19 2018 *)

PARI

a(n) = numerator((n-2)*(n+2)/(4*n^2))^2;
for(n=2, 50, print1(a(n), ", ")) \\ G. C. Greubel, Sep 19 2018

Formula

Sum_{n>=3} 1/a(n) = 79*Pi^2/192 - 65/18. - Amiram Eldar, Aug 14 2022