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A214691 G.f.: A(x) = Sum_{n>=0} x^n * Product_{k=1..n} (2^(2*k-1) - 1) / (1 + 2^(2*k-1)*x). 1
1, 1, 5, 151, 19025, 9702751, 19851828545, 162586475783551, 5327308465523832065, 698250320576208668759551, 366082867573618138109269955585, 767730685732013278335855487355082751, 6440190236715680978727827356359771295535105 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

A variant of A005014. Equals row sums (unsigned) of triangle A214690.

LINKS

Table of n, a(n) for n=0..12.

FORMULA

a(n) = 2*(4^(n-1) - 1)*a(n-1) - (-1)^n for n>0 with a(0)=1.

PROG

(PARI) {a(n)=if(n==0, 1, 2*(4^(n-1)-1)*a(n-1) - (-1)^n)}

(PARI) {a(n)=local(A=x); A=sum(m=0, n, x^m*prod(j=1, m, (2^(2*j-1)-1)/(1+x*2^(2*j-1))+x*O(x^n))); polcoeff(A, n, x)}

for(n=0, 20, print1(a(n), ", "));

CROSSREFS

Cf. A005014 (variant), A214690.

Sequence in context: A332115 A262655 A075598 * A261822 A105230 A222768

Adjacent sequences:  A214688 A214689 A214690 * A214692 A214693 A214694

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jul 26 2012

STATUS

approved

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Last modified March 28 14:04 EDT 2020. Contains 333089 sequences. (Running on oeis4.)