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 A249327 Rectangular array T(n,k) = f(n)*k^2, where f = A005117 (squarefree numbers); n, k >= 1; read by antidiagonals. 5
 1, 4, 2, 9, 8, 3, 16, 18, 12, 5, 25, 32, 27, 20, 6, 36, 50, 48, 45, 24, 7, 49, 72, 75, 80, 54, 28, 10, 64, 98, 108, 125, 96, 63, 40, 11, 81, 128, 147, 180, 150, 112, 90, 44, 13, 100, 162, 192, 245, 216, 175, 160, 99, 52, 14, 121, 200, 243, 320, 294, 252, 250 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Every positive integer occurs exactly once. LINKS Table of n, a(n) for n=1..62. FORMULA T(1,k) = A000290(k), T(2,k) = A001105(k), T(3,k) = A033428(k), T(4,k) = A033429(k), T(5,.) through T(10,.) are A033581, A033582, A033583, A033584, A152742 and A144555 without initial 0. - M. F. Hasler, Oct 31 2014 EXAMPLE Northwest corner: 1 4 9 16 25 36 49 2 8 18 32 50 72 98 3 12 27 48 75 108 147 5 20 45 80 125 180 245 6 24 54 96 150 216 294 MATHEMATICA z = 20; f = Select[Range[10000], SquareFreeQ[#] &]; u[n_, k_] := f[[n]]*k^2; t = Table[u[n, k], {n, 1, 20}, {k, 1, 20}]; TableForm[t] (* A249327 array *) Table[u[k, n - k + 1], {n, 1, 15}, {k, 1, n}] // Flatten (* A249327 sequence *) CROSSREFS Cf. A005117, A000037 (is partitioned by the rows of A249327, excluding the first). Sequence in context: A243968 A104583 A278103 * A182728 A290538 A097664 Adjacent sequences: A249324 A249325 A249326 * A249328 A249329 A249330 KEYWORD nonn,tabl,easy AUTHOR Clark Kimberling, Oct 26 2014 STATUS approved

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Last modified August 15 10:38 EDT 2024. Contains 375173 sequences. (Running on oeis4.)