2190397

Appears in sequences

• Indices of square numbers which are also heptagonal.at n=6A046196
• 40*n^2 + 9 is a square.at n=13A075873
• G.f.: (2*x^2+4*x+3)/((2*x+2)*sqrt(-4*x^3-4*x^2+1))-1/(2*x+2).at n=19A247171