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!)
A281868 Number of sets of exactly eight positive integers <= n having a square element sum. 2
1, 1, 3, 13, 34, 86, 197, 405, 786, 1446, 2532, 4263, 6938, 10953, 16837, 25281, 37165, 53605, 75999, 106075, 145951, 198199, 265921, 352825, 463320, 602609, 776797, 993007, 1259503, 1585839, 1983013, 2463629, 3042066, 3734648, 4559849, 5538527, 6694180 (list; graph; refs; listen; history; text; internal format)
OFFSET

8,3

LINKS

Alois P. Heinz, Table of n, a(n) for n = 8..1000

EXAMPLE

a(8) = 1: {1,2,3,4,5,6,7,8}.

a(10) = 3: {1,2,3,4,5,6,7,8}, {1,3,5,6,7,8,9,10}, {2,3,4,6,7,8,9,10}.

MAPLE

b:= proc(n, i, t) option remember;

      `if`(i<t, 0, `if`(n=0, `if`(t=0, 1, 0),

      `if`(t<1 or n<t*(t+1)/2 or n>(t+1)*(2*i-t)/2, 0,

      `if`(i>n, 0, b(n-i, i-1, t-1))+b(n, i-1, t))))

    end:

a:= proc(n) option remember; `if`(n<0, 0, a(n-1)+add(

       b(j^2-n, n-1, 7), j=isqrt(n-28)..isqrt(8*n-28)))

    end:

seq(a(n), n=8..60);

CROSSREFS

Column k=8 of A281871.

Sequence in context: A211801 A016061 A154154 * A137976 A095661 A058214

Adjacent sequences:  A281865 A281866 A281867 * A281869 A281870 A281871

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Feb 01 2017

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 10 04:38 EDT 2020. Contains 336368 sequences. (Running on oeis4.)