A332969 a(n) = [x^n] (Sum_{j>=0} A002193(1-j) * x^j)^2.

1, 8, 18, 16, 37, 26, 34, 52, 70, 90, 87, 116, 127, 112, 157, 212, 158, 192, 252, 252, 249, 272, 349, 276, 287, 478, 482, 334, 407, 478, 465, 488, 544, 698, 562, 504, 682, 698, 738, 736, 742, 880, 907, 826, 944, 848, 998, 1110, 976, 1106, 1217, 1112, 1060

Offset: 0

Author

Andrew Slattery, Mar 04 2020

Keywords

• nonn
• base
• easy

Examples

			a(1) = 8 because the coefficient of x^1 in (1 + 4x + ... )^2 is 8.
		

Crossrefs

Cf. A002193.

Programs

PARI

seq(n)={Vec(Ser(digits(sqrtint(2*100^n)))^2)} \\ Andrew Howroyd, Mar 04 2020

Formula

G.f.: (Sum_{j>=0} A002193(1-j) * x^j)^2.

Sum_{k>=0} a(k)/10^k = 2.

a(n) = Sum_{j=0..n} A002193(1-j)*A002193(j-n+1).