A062788 Squares of the form 5n*(n-1)+1.

1, 361, 116281, 37442161, 12056259601, 3882078149401, 1250017107847561, 402501626648765281, 129604273763794572961, 41732173650315203728201, 13437630311127731805907801, 4326875228009479326298583761, 1393240385788741215336338063281

Offset

1,2

Links

Table of n, a(n) for n=1..13.

Index entries for linear recurrences with constant coefficients, signature (323,-323,1).

Formula

a(n) = A049683(2*n-1) = (1/16) * (Lucas(12*n-6) - 2). - Joerg Arndt, Apr 09 2023

From Chai Wah Wu, Apr 17 2024: (Start)

a(n) = 323*a(n-1) - 323*a(n-2) + a(n-3) for n > 3.

G.f.: x*(-x^2 - 38*x - 1)/((x - 1)*(x^2 - 322*x + 1)). (End)

Prog

(PARI) for(n=1, 10^8, x=(5*n*(n-1)+1); if(issquare(x), print(x)))

Crossrefs

Bisection of A049683.

Cf. A062786.

Sequence in context: A232081 A231770 A145121 * A048289 A191216 A337729

Adjacent sequences: A062785 A062786 A062787 * A062789 A062790 A062791

Keyword

nonn,easy,changed

Author

Jason Earls, Jul 19 2001

Extensions

More terms from Sean A. Irvine, Apr 08 2023

Status

approved