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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.

A258323 Sum T(n,k) over all partitions lambda of n into k distinct parts of Product_{i:lambda} prime(i); triangle T(n,k), n>=0, 0<=k<=A003056(n), read by rows.

Original entry on oeis.org

1, 0, 2, 0, 3, 0, 5, 6, 0, 7, 10, 0, 11, 29, 0, 13, 43, 30, 0, 17, 94, 42, 0, 19, 128, 136, 0, 23, 231, 293, 0, 29, 279, 551, 210, 0, 31, 484, 892, 330, 0, 37, 584, 1765, 852, 0, 41, 903, 2570, 1826, 0, 43, 1051, 4273, 4207, 0, 47, 1552, 6747, 6595, 2310
Offset: 0

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Author

Alois P. Heinz, May 26 2015

Keywords

Examples

			T(6,2) = 43 because the partitions of 6 into 2 distinct parts are {[5,1], [4,2]} and prime(5)*prime(1) + prime(4)*prime(2) = 11*2 + 7*3 = 22 + 21 = 43.
Triangle T(n,k) begins:
  1
  0,  2;
  0,  3;
  0,  5,   6;
  0,  7,  10;
  0, 11,  29;
  0, 13,  43,  30;
  0, 17,  94,  42;
  0, 19, 128, 136;
  0, 23, 231, 293;
  0, 29, 279, 551, 210;
		

Crossrefs

Row sums give A147655.
T(n*(n+1)/2,n) = A002110(n).
T(n^2,n) = A321267(n).

Programs

  • Maple
    g:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0, expand(
          add(g(n-i*j, i-1)*(ithprime(i)*x)^j, j=0..min(1, n/i)))))
        end:
    T:= n-> (p-> seq(coeff(p, x, i), i=0..degree(p)))(g(n$2)):
    seq(T(n), n=0..20);
  • Mathematica
    g[n_, i_] := g[n, i] = If[n==0, 1, If[i<1, 0, Expand[Sum[g[n-i*j, i-1] * (Prime[i]*x)^j, {j, 0, Min[1, n/i]}]]]]; T[n_] := Function[p, Table[ Coefficient[p, x, i], {i, 0, Exponent[p, x]}]][g[n, n]]; Table[T[n], {n, 0, 20}] // Flatten (* Jean-François Alcover, Jan 06 2017, after Alois P. Heinz *)