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A117261 Row sums of triangle A117260. 0
1, 2, 5, 21, 169, 2705, 86561, 5539905, 709107841, 181531607297, 92944182936065, 95174843326530561, 194918079132734588929, 798384452127680876253185, 6540365431829961738266091521, 107157347235102093119751643480065 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..15.

FORMULA

a(n) = Sum_{k=0..n} 2^(n*(n-1)/2 - k*(k-1)/2).

PROG

(PARI) a(n)=sum(k=0, n, 2^((n-k)*(n+k-1)/2))

CROSSREFS

Sequence in context: A144271 A193189 A176527 * A108021 A162437 A216756

Adjacent sequences:  A117258 A117259 A117260 * A117262 A117263 A117264

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Mar 14 2006

STATUS

approved

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Last modified June 19 17:57 EDT 2013. Contains 226415 sequences.