A136650 - OEIS

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A136650

Self-convolution of A006125(n) = 2^{n(n-1)/2}.

1, 2, 5, 20, 148, 2208, 67904, 4264960, 541216768, 137984868352, 70507295670272, 72128242290524160, 147646152060442771456, 604610628447525580832768, 4952364915780360673188380672, 81134591384874923825347187179520 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,2`
	FORMULA	`a(n) = Sum_{k=0..n} 2^{ k(k-1)/2 + (n-k)(n-k-1)/2 }.`
	PROG	`(PARI) a(n)=sum(k=0, n, 2^(k(k-1)/2 + (n-k)(n-k-1)/2))`
	CROSSREFS	`Sequence in context: A012317 A118181 A140988 * A111885 A159320 A184730` `Adjacent sequences: A136647 A136648 A136649 * A136651 A136652 A136653`
	KEYWORD	`nonn`
	AUTHOR	`Paul D. Hanna (pauldhanna(AT)juno.com), Jan 16 2008`

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Last modified February 15 07:22 EST 2012. Contains 205706 sequences.