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A195509 E.g.f.: (exp(x*exp(x)) + exp(x/exp(x)))/2. 0
1, 1, 1, 4, 25, 96, 481, 3368, 20721, 141760, 1146721, 9098112, 77652169, 726208640, 6891125697, 69344336896, 738718169569, 8076031881216, 92647353941569, 1106883171037184, 13616813607795321, 174298975125127168, 2304515271134124577 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..22.

FORMULA

E.g.f.: Sum_{n>=0} x^n*cosh(n*x)/n!.

a(n) = sum(m=0..floor((n)/2), binomial(n+1,2*m)*(n-2*m+1)^(2*m)). [Vladimir Kruchinin, Mar 10 2013]

EXAMPLE

E.g.f.: A(x) = 1 + x + x^2/2! + 4*x^3/3! + 25*x^4/4! + 96*x^5/5! + 481*x^6/6! +...

PROG

(PARI) {a(n)=local(X=x+x*O(x^n), A=1+X); A=(exp(X*exp(X))+exp(X/exp(X)))/2; n!*polcoeff(A, n)}

(PARI) {a(n)=n!*polcoeff(sum(m=0, n, x^m*cosh(m*x+x*O(x^n))/m!), n)}

CROSSREFS

Sequence in context: A027764 A095669 A323967 * A027949 A226547 A264167

Adjacent sequences:  A195506 A195507 A195508 * A195510 A195511 A195512

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Sep 19 2011

STATUS

approved

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Last modified June 25 12:01 EDT 2019. Contains 324352 sequences. (Running on oeis4.)