id:A025262 - OEIS Search Results

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a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ...+ a(n-1)*a(1) for n >= 4.

+0
3

1, 1, 1, 3, 8, 23, 68, 207, 644, 2040, 6558, 21343, 70186, 232864, 778550, 2620459, 8872074, 30195288, 103246502, 354508628, 1221846856, 4225644866, 14659644348, 51002664023, 177909901566, 622093882290, 2180123564130, 7656055966092 (list; graph; listen)

	OFFSET	`1,4`
	LINKS	`M. Somos, Number Walls in Combinatorics.`
	FORMULA	`G.f.: (1-sqrt(1-4x+4x^3))/2. Satisfies A(x)-A(x)^2=x-x^3 - Michael Somos, Aug 04, 2000.`
	PROGRAM	`(PARI) a(n)=polcoeff((1-sqrt(1-4x+4x^3+x*O(x^n)))/2, n)`
	CROSSREFS	`Essentially same as A056010.` `Sequence in context: A025578 A038151 A057198 this_sequence A056010 A002712 A005960` `Adjacent sequences: A025259 A025260 A025261 this_sequence A025263 A025264 A025265`
	KEYWORD	`nonn`
	AUTHOR	`Clark Kimberling (ck6(AT)evansville.edu)`

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Last modified July 19 08:04 EDT 2008. Contains 142098 sequences.

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