A105837 Numbers n such that n^2 = 11*m^2 + 11*m + 1.

1, 131, 529, 52139, 210541, 20751191, 83794789, 8258921879, 33350115481, 3287030156651, 13273262166649, 1308229743425219, 5282724992210821, 520672150853080511, 2102511273637740109, 207226207809782618159, 836794204182828352561

Offset

1,2

Links

Table of n, a(n) for n=1..17.

Index entries for linear recurrences with constant coefficients, signature (0,398,0,-1).

Formula

a(1)=1, a(2)=131, a(3)=398*a(1)+a(2), a(4)=398*a(2)+a(1), a(n)=398*a(n-2)-a(n-4) for n>4.

G.f.: x*(1+x)*(1+130*x+x^2)/((1-20*x+x^2)*(1+20*x+x^2)). [Bruno Berselli, Feb 21 2013]

Mathematica

LinearRecurrence[{0, 398, 0, -1}, {1, 131, 529, 52139}, 17]

Crossrefs

Cf. A105838 (associated m).

Sequence in context: A276255 A142555 A118507 * A142205 A142807 A103834

Adjacent sequences: A105834 A105835 A105836 * A105838 A105839 A105840

Keyword

nonn,easy

Author

Pierre CAMI, Apr 22 2005

Extensions

More terms from Bruno Berselli, Feb 21 2013

Status

approved