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 A103218 Triangle read by rows: T(n, k) = (2*k+1)*(n+1-k)^2. 1
 1, 4, 3, 9, 12, 5, 16, 27, 20, 7, 25, 48, 45, 28, 9, 36, 75, 80, 63, 36, 11, 49, 108, 125, 112, 81, 44, 13, 64, 147, 180, 175, 144, 99, 52, 15, 81, 192, 245, 252, 225, 176, 117, 60, 17, 100, 243, 320, 343, 324, 275, 208, 135, 68, 19, 121, 300, 405, 448, 441, 396, 325, 240 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS The triangle is generated from the product A * B of the infinite lower triangular matrix A = 1 0 0 0... 3 1 0 0... 5 3 1 0... 7 5 3 1... ... and B = 1 0 0 0... 1 3 0 0... 1 3 5 0... 1 3 5 7... ... LINKS EXAMPLE Triangle begins: 1, 4,3, 9,12,5, 16,27,20,7, 25,48,45,28,9, MATHEMATICA T[n_, k_] := (2*k + 1)*(n + 1 - k)^2; Flatten[ Table[ T[n, k], {n, 0, 10}, {k, 0, n}]] (* Robert G. Wilson v, Feb 10 2005 *) PROG (PARI) T(n, k) = (2*k+1)*(n+1-k)^2; for(i=0, 10, for(j=0, i, print1(T(i, j), ", ")); print()) CROSSREFS Row sums give A002412 (hexagonal pyramidal numbers). T(n, 0)=A000290(n+1) (the squares); T(n, 1)=3*n^2=A033428(n); T(n, 2)=5*n^2=A033429(n+1); T(n, 3)=7*n^2=A033582(n+2); Cf. A103219 (product B*A), A002412, A000290. Sequence in context: A131805 A197694 A187770 * A319311 A107381 A242531 Adjacent sequences:  A103215 A103216 A103217 * A103219 A103220 A103221 KEYWORD nonn,tabl AUTHOR Lambert Klasen (lambert.klasen(AT)gmx.de) and Gary W. Adamson, Jan 25 2005 STATUS approved

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Last modified January 21 11:11 EST 2020. Contains 331105 sequences. (Running on oeis4.)