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A129653 Diagonal sums of number triangle A129652. 1
1, 1, 4, 15, 83, 556, 4435, 40773, 423836, 4908403, 62606297, 871421976, 13136605577, 213122669141, 3701085673676, 68480774296803, 1344611320542931, 27917413103561540, 611000785570868627, 14056645627856206809 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..19.

T.-X. He, A symbolic operator approach to power series transformation-expansion formulas, JIS 11 (2008) 08.2.7

FORMULA

a(n) = Sum_{k=0..floor(n/2)} (((n-k)!/k!)*sum{i=0..n-2k} C(n-2k-1,i)/(n-2k-i)!).

PROG

(PARI) a(n) = sum(k=0, n\2, ((n-k)!/k!)*sum(i=0, n-2*k, binomial(n-2*k-1, i)/(n-2*k-i)!)); \\ Michel Marcus, Sep 10 2015

CROSSREFS

Cf. A129652.

Sequence in context: A207161 A203121 A232220 * A081722 A117927 A143340

Adjacent sequences:  A129650 A129651 A129652 * A129654 A129655 A129656

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Apr 26 2007

STATUS

approved

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Last modified September 25 19:18 EDT 2021. Contains 347659 sequences. (Running on oeis4.)