login
A195060
Numbers on the main diagonals and on the axes (x,y) in the square spiral whose vertices are the generalized pentagonal numbers A001318.
0
0, 1, 2, 3, 5, 6, 7, 9, 12, 13, 15, 18, 22, 24, 26, 30, 35, 37, 40, 45, 51, 54, 57, 63, 70, 73, 77, 84, 92, 96, 100, 108, 117, 121, 126, 135, 145, 150, 155, 165, 176, 181, 187, 198, 210, 216, 222, 234, 247, 253, 260, 273, 287, 294, 301, 315, 330
OFFSET
0,3
COMMENTS
Union of A001318, A032528 and A045943, without repetitions.
FORMULA
a(2*n) = A001318(n). a(4*n+1) = A032528(n+1). a(4*n+3) = A045943(n+1).
Conjectures: a(n) = 2*a(n-1) - 2*a(n-2) + 2*a(n-3) - a(n-4) + a(n-8) - 2*a(n-9) + 2*a(n-10) - 2*a(n-11) + a(n-12); g.f.: -x*(1+x^2+x^3-x^4+x^5+x^7-2*x^8+x^11+2*x^9-2*x^10) / ( (1+x)*(x^4+1)*(x^2+1)^2*(x-1)^3 ). - R. J. Mathar, Oct 11 2011
CROSSREFS
KEYWORD
nonn
AUTHOR
Omar E. Pol, Sep 08 2011
STATUS
approved