A106331 Numbers j such that 24*(j^2) + 25 = k^2.
0, 1, 2, 5, 12, 21, 50, 119, 208, 495, 1178, 2059, 4900, 11661, 20382, 48505, 115432, 201761, 480150, 1142659, 1997228, 4752995, 11311158, 19770519, 47049800, 111968921, 195707962, 465745005, 1108378052, 1937309101, 4610400250
Offset: 1
Links
- Index entries for linear recurrences with constant coefficients, signature (0,0,10,0,0,-1). [_R. J. Mathar_, May 22 2010]
Crossrefs
Cf. A106330.
Formula
j(1)=0, j(2)=1, j(3)=2, j(4)=5, j(5)=10*j(2)+j(3), j(6)=10*j(3)+j(2), j(7)=10*j(4)+j(1) then j(n)=10*j(n-3)-j(n-6).
a(n) = +10*a(n-3) -a(n-6). G.f.: x^2*(1+2*x+5*x^2+2*x^3+x^4)/(1-10*x^3+x^6). [R. J. Mathar, May 22 2010]
Extensions
More terms from Jon E. Schoenfield, May 16 2010
Comments