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A105614 Self-convolution of A105613. 1
1, 2, 3, 6, 11, 12, 24, 48, 71, 78, 155, 272, 420, 652, 903, 1364, 2144, 3436, 5955, 9668, 10838, 16408, 27948, 45920, 66817, 109296, 152786, 197542, 327755, 531440, 735565, 1083128, 1727206, 2521374, 3938246, 5248706, 8452114, 12093692 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..37.

EXAMPLE

Given sequence A105613:

[1, 1, 1, 2,3, 1, 6,11,12, 1, 24,48,71,78, ...],

the self-convolution yields this sequence:

[1, 2,3, 6,11,12, 24,48,71,78, ...],

which is A105613 with 1's omitted at positions {0,2,5,9,14,...}.

PROG

(PARI) {a(n)=local(V, t); if(n==0, 1, V=vector(n+1, k, t=ceil((sqrt(8*k+1)-1)/2); if(ceil((sqrt(8*k+9)-1)/2)-t==1, 1, a(k-t))); polcoeff(Ser(V)^2+x*O(x^n), n))}

CROSSREFS

Cf. A105613.

Sequence in context: A284091 A004038 A152038 * A116441 A116051 A124593

Adjacent sequences:  A105611 A105612 A105613 * A105615 A105616 A105617

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Apr 16 2005

STATUS

approved

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Last modified June 23 12:08 EDT 2021. Contains 345401 sequences. (Running on oeis4.)