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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A132317 a(n) = [x^(2^n)] Product_{i=0..n} (1 + x^(2^i) )^(2^(n-i)); equals column 1 of triangle A132318. 2
1, 2, 15, 1024, 7048181, 469389728563470, 2954306864416502250656677496683, 165756604793755389851497802171770083459242616940095659925793836 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Next term, a(8), has 126 digits.

LINKS

Table of n, a(n) for n=0..7.

EXAMPLE

a(0) = [x] (1+x) = 1;

a(1) = [x^2] (1+x)^2*(1+x^2) = 2;

a(2) = [x^4] (1+x)^4*(1+x^2)^2*(1+x^4) = 15;

a(3) = [x^8] (1+x)^8*(1+x^2)^4*(1+x^4)^2*(1+x^8) = 1024;

a(4) = [x^16] (1+x)^16*(1+x^2)^8*(1+x^4)^4*(1+x^8)^2*(1+x^16) = 7048181.

PROG

(PARI) {a(n)=polcoeff(prod(i=0, n, (1 + x^(2^i) +x*O(x^(2^n)))^(2^(n-i))), 2^n)}

CROSSREFS

Cf. A132318, A132316.

Sequence in context: A007542 A090604 A007467 * A068409 A096232 A193869

Adjacent sequences:  A132314 A132315 A132316 * A132318 A132319 A132320

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Aug 19 2007

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 August 13 08:27 EDT 2020. Contains 336442 sequences. (Running on oeis4.)