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!)
A157554 Half the number of length n integer sequences with sum zero and sum of squares 968. 1
1, 3, 66, 3990, 178335, 6510483, 190667659, 5047394427, 131071431060, 3262733109790, 78872812374741, 1857536871457917, 41896936373100900, 899337065318075790, 18460566561637223550, 365127965985604164628 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,2

LINKS

R. H. Hardin, Table of n, a(n) for n=2..50

FORMULA

[cache enabling] count(n,s,ss)->count(n,t,tt) where t=s mod n, q=(t-s)/n, tt=ss+2*q*s+n*q^2; count(n,t,tt)=sum[i^2<=tt]{ count(n-1,t-i,tt-i^2) }. a(n)=count(n,0,968)/2.

CROSSREFS

Sequence in context: A157543 A157984 A187547 * A185053 A165655 A157576

Adjacent sequences:  A157551 A157552 A157553 * A157555 A157556 A157557

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 02 2009

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 October 22 21:58 EDT 2020. Contains 337962 sequences. (Running on oeis4.)