cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A323891 a(n) is the number of partitions of 72*n + 42 into 10 odd squares.

Original entry on oeis.org

2, 9, 22, 41, 68, 106, 154, 212, 285, 368, 477, 598, 741, 898, 1076, 1286, 1524, 1785, 2068, 2379, 2741, 3131, 3554, 4002, 4497, 5044, 5644, 6274, 6939, 7653, 8445, 9295, 10186, 11117, 12113, 13192, 14355, 15556, 16807, 18147, 19570, 21089, 22673, 24300, 26029, 27865, 29821, 31822, 33894, 36088
Offset: 0

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Author

Marius A. Burtea, Feb 12 2019

Keywords

Examples

			For n=0, 72*0+42 = 42 = 25+9+1+1+1+1+1+1+1+1 = 9+9+9+9+1+1+1+1+1+1, so a(0)=2.
For n=1, 72*1+42 = 114 = 81+25+1+1+1+1+1+1+1+1 = 81+9+9+9+1+1+1+1+1+1 = 49+49+9+1+1+1+1+1+1+1 = 49+25+25+9+1+1+1+1+1+1 = 49+25+9+9+9+9+1+1+1+1 = 49+9+9+9+9+9+9+9+1+1 = 25+25+25+25+9+1+1+1+1+1 = 25+25+25+9+9+9+9+1+1+1 = 25+25+9+9+9+9+9+9+9+1, so a(1)=9.
		

References

  • Laurențiu Panaitopol, Alexandru Gica, Arithmetic problems and number theory, Ed. Gil, Zalău, (2006), ch. 14, p. 85, pr. 32. (in Romanian).

Crossrefs

Programs

  • Magma
    [#RestrictedPartitions(72*n+42, 10, {(2*d+1)^2:d in [0..100]}): n in [0..100]];
  • Maple
    S:= proc(n, k, m)
       option remember;
       local p,j;
       if k = 0 then if n = 0 then return 1 else return 0 fi
       elif m < 1 then return 0
       elif n < k then return 0
       elif n > k*m^2 then return 0
       fi;
       if m^2 > n then
         p:= floor(sqrt(n));
         if p::even then p:= p-1 fi;
         return procname(n, k, p)
       fi;
       add(procname(n-j*m^2,k-j,m-2), j=0..n/m^2)
    end proc:
    seq(S(72*n+42, 10, 72*n+42), n=0..100); # Robert Israel, Feb 24 2019
  • Mathematica
    a[n_] := IntegerPartitions[72n+42, {10}, Select[ Range[1, 72n+42, 2], IntegerQ@Sqrt@#&]] // Length;
    Table[a[n], {n, 0, 100}] (* Jean-François Alcover, Sep 19 2022 *)