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A173612 Odd bisection of A173610. 3
1, 4, 25, 144, 1024, 7396, 51076, 345744, 2547216, 19114384, 145564225, 1111822336, 8343726336, 62292173056, 459542986816, 3371072258304, 25398293867584, 192578234089536, 1474993183809600, 11338593510740224 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..19.

FORMULA

a(n) = A173611(n)^2, where A173611 is the self-convolution of A173610.

EXAMPLE

G.f.: A(x) = 1 + 4*x + 25*x^2 + 144*x^3 + 1024*x^4 + 7396*x^5 +...

Describe the g.f. of A173610 by:

B(x) = 1 + x + 2*x^2 + 4*x^3 + 10*x^4 + 25*x^5 + 60*x^6 + 144*x^7 +...

then the g.f. of A173611 is given by C(x) = B(x)^2:

C(x) = 1 + 2*x + 5*x^2 + 12*x^3 + 32*x^4 + 86*x^5 +...

where the square of the coefficients of C(x) form this sequence

and yields the odd bisection of A173610.

PROG

(PARI) {a(n)=local(A=1+x, B); for(i=1, n, B=(A+x*O(x^n))^2; A=1+x*sum(m=0, n\2, polcoeff(B, m)*polcoeff(B, m+1)*x^(2*m+1)) +x*sum(m=0, n\2, polcoeff(B, m)^2*x^(2*m))); polcoeff(A^2, n)^2}

CROSSREFS

Cf. A173610, A173611, A173613.

Sequence in context: A301836 A275177 A079291 * A072221 A302064 A221849

Adjacent sequences:  A173609 A173610 A173611 * A173613 A173614 A173615

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Feb 22 2010

STATUS

approved

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Last modified September 21 11:46 EDT 2020. Contains 337268 sequences. (Running on oeis4.)