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A324616 G.f.: Sum_{n>=0} (2^n + q)^n * x^n / (1 + 2^n*q*x)^(n+1), where q = sqrt(2). 0
1, 2, 12, 416, 59528, 32265472, 67721176080, 560073696753664, 18415259721236185120, 2416524076310084112760832, 1267433026502703401885538910272, 2658316556785488750691847530918313984, 22300394287673273128207029214065419602624640, 748285359413327989637421924090871932680071306805248, 100433491577808064702053548387551557378968553711590149456128 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Note that the generating function, which involves an irrational constant, expands as a power series in x that consists solely of integer coefficients.

LINKS

Table of n, a(n) for n=0..14.

FORMULA

G.f.: Sum_{n>=0} (2^n + q)^n * x^n / (1 + 2^n*q*x)^(n+1), where q = sqrt(2).

G.f.: Sum_{n>=0} (2^n - q)^n * x^n / (1 - 2^n**qx)^(n+1), where q = sqrt(2).

a(n) = Sum_{k=0..n} binomial(n,k) * (2^n - 2^k*q)^(n-k) * q^k, where q = sqrt(2).

a(n) = Sum_{k=0..n} binomial(n,k) * (2^n + 2^k*q)^(n-k) * (-q)^k, where q = sqrt(2).

EXAMPLE

G.f.: A(x) = 1 + 2*x + 12*x^2 + 416*x^3 + 59528*x^4 + 32265472*x^5 + 67721176080*x^6 + 560073696753664*x^7 + 18415259721236185120*x^8 + ...

Let q = sqrt(2), then

A(x) = 1/(1+q*x) + (2 + q)*x/(1 + 2*q*x)^2 + (2^2 + q)^2*x^2/(1 + 2^2*q*x)^3 + (2^3 + q)^3*x^3/(1 + 2^3*q*x)^3 + (2^4 + q)^4*x^4/(1 + 2^4*q*x)^5 + (2^5 + q)^5*x^5/(1 + 2^5*q*x)^6 + (2^6 + q)^6*x^6/(1 + 2^6*q*x)^7 + ...

and also

A(x) = 1/(1-q*x) + (2 - q)*x/(1 - 2*q*x)^2 + (2^2 - q)^2*x^2/(1 - 2^2*q*x)^3 + (2^3 - q)^3*x^3/(1 - 2^3*q*x)^3 + (2^4 - q)^4*x^4/(1 - 2^4*q*x)^5 + (2^5 - q)^5*x^5/(1 - 2^5*q*x)^6 + (2^6 - q)^6*x^6/(1 - 2^6*q*x)^7 + ...

PROG

(PARI) {a(n) = my(q=sqrt(2), A = sum(m=0, n+1, (2^m + q)^m*x^m/(1 + 2^m*q*x +x*O(x^n) )^(m+1) )); round( polcoeff(A, n) )}

for(n=0, 20, print1(a(n), ", "))

(PARI) {a(n) = my(q=sqrt(2), A = sum(m=0, n+1, (2^m - q)^m*x^m/(1 - 2^m*q*x +x*O(x^n) )^(m+1) )); round( polcoeff(A, n) )}

for(n=0, 20, print1(a(n), ", "))

(PARI) {a(n) = my(q=sqrt(2)); round( sum(k=0, n, binomial(n, k) * (2^n - 2^k*q)^(n-k) * q^k ) )}

for(n=0, 20, print1(a(n), ", "))

(PARI) {a(n) = my(q=sqrt(2)); round( sum(k=0, n, binomial(n, k) * (2^n + 2^k*q)^(n-k) * (-q)^k ) )}

for(n=0, 20, print1(a(n), ", "))

CROSSREFS

Cf. A324306.

Sequence in context: A229919 A287679 A051009 * A060942 A072446 A220113

Adjacent sequences:  A324613 A324614 A324615 * A324617 A324618 A324619

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Mar 13 2019

STATUS

approved

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Last modified November 28 12:38 EST 2021. Contains 349403 sequences. (Running on oeis4.)