A220692 Square array A220691 transposed.

0, 1, 0, 3, 0, 0, 6, 1, 1, 0, 10, 2, 1, 0, 0, 15, 4, 2, 1, 0, 0, 21, 6, 4, 1, 1, 0, 0, 28, 9, 5, 2, 2, 0, 0, 0, 36, 12, 7, 3, 2, 1, 0, 0, 0, 45, 16, 10, 5, 3, 2, 1, 0, 0, 0, 55, 20, 12, 6, 4, 2, 2, 0, 0, 0, 0, 66, 25, 15, 8, 6, 3, 3, 1, 0, 0, 0, 0

Offset: 1

Author

Antti Karttunen, Feb 18 2013

Keywords

• nonn
• tabl

Links

• Index entries for sequences related to subset sums modulo m

Crossrefs

Cf. A220691, A220693, A061857.

Programs

Mathematica

a[n_, 1] := n*(n-1)/2; a[n_, k_] := Module[{r}, r = Reduce[1 <= i < j <= n && Mod[i+j, k] == 0, {i, j}, Integers]; Which[Head[r] === Or, Length[r], Head[r] === And, 1, r === False, 0, True, Print[r, " not parsed"]]]; Table[a[n-k+1, k], {n, 1, 13} , {k, 1, n}] // Flatten (* Jean-François Alcover, Mar 04 2014 *)

Scheme

(define (A220692 n) (A220691bi (A004736 n) (A002260 n)))

Formula

a(n) = A220691bi(A004736(n),A002260(n)). (As a sequence. As an array this is the transpose of the square array given in A220691).