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.

A208475 Triangle read by rows: T(n,k) = total sum of odd/even parts >= k in all partitions of n, if k is odd/even.

Original entry on oeis.org

1, 2, 2, 7, 2, 3, 10, 10, 3, 4, 23, 12, 11, 4, 5, 36, 30, 17, 14, 5, 6, 65, 40, 35, 18, 17, 6, 7, 94, 82, 49, 44, 22, 20, 7, 8, 160, 110, 93, 58, 48, 26, 23, 8, 9, 230, 190, 133, 108, 70, 56, 30, 26, 9, 10, 356, 260, 217, 148, 124, 76, 64, 34, 29, 10, 11
Offset: 1

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Author

Omar E. Pol, Feb 28 2012

Keywords

Comments

Essentially this sequence is related to A206561 in the same way as A206563 is related to A181187. See the calculation in the example section of A206563.

Examples

			Triangle begins:
1;
2,   2;
7,   2,  3;
10, 10,  3,  4;
23, 12, 11,  4,  5;
36, 30, 17, 14,  5,  6;
		

Crossrefs

Column 1-2: A066967, A066966. Right border is A000027.

Programs

  • Maple
    p:= (f, g)-> zip((x, y)-> x+y, f, g, 0):
    b:= proc(n, i) option remember; local f, g;
          if n=0 then [1]
        elif i=1 then [1, n]
        else f:= b(n, i-1); g:= `if`(i>n, [0], b(n-i, i));
             p (p (f, g), [0$i, g[1]])
          fi
        end:
    T:= proc(n) local l;
          l:= b(n, n);
          seq (add (l[i+2*j+1]*(i+2*j), j=0..(n-i)/2), i=1..n)
        end:
    seq (T(n), n=1..14);  # Alois P. Heinz, Mar 21 2012
  • Mathematica
    p[f_, g_] := With[{m = Max[Length[f], Length[g]]}, PadRight[f, m, 0] + PadRight[g, m, 0]]; b[n_, i_] := b[n, i] = Module[{f, g}, Which[n == 0, {1}, i == 1, {1, n}, True, f = b[n, i-1]; g = If[i>n, {0}, b[n-i, i]]; p[p[f, g], Append[Array[0&, i], g[[1]]]]]]; T[n_] := Module[{l}, l = b[n, n]; Table[Sum[l[[i+2j+1]]*(i+2j), {j, 0, (n-i)/2}], {i, 1, n}]]; Table[T[n], {n, 1, 14}] // Flatten (* Jean-François Alcover, Mar 11 2015, after Alois P. Heinz *)

Extensions

More terms from Alois P. Heinz, Mar 21 2012