login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A202942 G.f.: [ Sum_{n>=0} (n+1)*(n+2)/2 * 2^(n^2) * x^n ]^(1/3). 4
1, 2, 28, 1592, 320416, 233502272, 640425828736, 6752822665196288, 276674110514780283136, 44326172948662599528407552, 27888135883706078415361423227904, 69119744225611603596101581358820128768, 676455661208111898411893322163207326229331968 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..12.

FORMULA

a(2*n) == 1 (mod 3); a(2*n+1) == 2 (mod 3).

EXAMPLE

G.f.: A(x) = 1 + 2*x + 28*x^2 + 1592*x^3 + 320416*x^4 + 233502272*x^5 +...

where

A(x)^3 = 1 + 3*2*x + 6*2^4*x^2 + 10*2^9*x^3 + 15*2^16*x^4 + 21*2^25*x^5 +...

PROG

(PARI) {a(n)=polcoeff(sum(m=0, n, (m+1)*(m+2)/2*2^(m^2)*x^m+x*O(x^n))^(1/3), n)}

CROSSREFS

Sequence in context: A071220 A063794 A238817 * A326366 A177400 A230700

Adjacent sequences:  A202939 A202940 A202941 * A202943 A202944 A202945

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Dec 26 2011

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 23 10:45 EST 2020. Contains 331171 sequences. (Running on oeis4.)