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A220692 Square array A220691 transposed. 2
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 (list; table; graph; refs; listen; history; text; internal format)
OFFSET
1,4
LINKS
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).
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 *)
PROG
(Scheme): (define (A220692 n) (A220691bi (A004736 n) (A002260 n)))
CROSSREFS
Sequence in context: A145225 A332442 A061480 * A048962 A135028 A325006
KEYWORD
nonn,tabl
AUTHOR
Antti Karttunen, Feb 18 2013
STATUS
approved

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Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)