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 A242287 Greedy-summable triangular numbers. 4
 10, 21, 28, 45, 55, 66, 91, 105, 120, 136, 171, 190, 231, 253, 300, 325, 378, 406, 435, 496, 528, 595, 630, 666, 703, 780, 820, 903, 946, 1035, 1081, 1176, 1225, 1326, 1378, 1485, 1540, 1596, 1711, 1770, 1891, 1953, 2080, 2145, 2211, 2278, 2415, 2485, 2628 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Greedy summability is defined at A242284. LINKS Clark Kimberling, Table of n, a(n) for n = 1..1000 EXAMPLE Let s(n) = n(n+1)/2 = A000217(n).  Then a(1) = 10 = 6 + 3 + 1; a(2) = 21 = 15 + 6; a(3) = 28 = 21 + 6 + 1; a(4) = 45 = 36 + 6 + 3. MATHEMATICA z = 200;  s = Table[n (n + 1)/2, {n, 1, z}]; t = Table[{s[[n]], #, Total[#] == s[[n]]} &[DeleteCases[-Differences[FoldList[If[#1 - #2 >= 0, #1 - #2, #1] &, s[[n]], Reverse[Select[s, # < s[[n]] &]]]], 0]], {n, z}] r[n_] := s[[n]] - Total[t[[n]][[2]]]; tr = Table[r[n], {n, 2, z}]  (* A242284 *) c = Table[Length[t[[n]][[2]]], {n, 2, z}] (* A242285 *) f = 1 + Flatten[Position[tr, 0]]  (* A242286 *) f (f + 1)/2  (* A242287 *) (* Peter J. C. Moses, May 06 2014 *) CROSSREFS Cf. A242284, A242285, A242286, A241833, A000217. Sequence in context: A181450 A087597 A087598 * A165403 A097386 A108685 Adjacent sequences:  A242284 A242285 A242286 * A242288 A242289 A242290 KEYWORD nonn,easy AUTHOR Clark Kimberling, May 10 2014 STATUS approved

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Last modified June 26 20:37 EDT 2019. Contains 324380 sequences. (Running on oeis4.)