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 A290262 Irregular triangle reasd by rows: rows give the (negated) nonzero coefficients of t in each term of the inverse power product expansion of 1 - t * x/(1-x). 6
 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 3, 4, 2, 1, 3, 5, 5, 3, 1, 1, 4, 9, 13, 13, 9, 4, 1, 1, 4, 9, 13, 13, 9, 4, 1, 1, 5, 14, 25, 30, 24, 12, 3, 1, 5, 15, 30, 42, 42, 30, 15, 5, 1, 1, 6, 21, 48, 75, 81, 60, 30, 10, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,7 COMMENTS Row sums are A290261(n). A regular version is A290320. LINKS EXAMPLE Triangle begins:   1;   1,  1;   1,  1,   1,  2,  2,  1;   1,  2,  2,  1;   1,  3,  4,  2;   1,  3,  5,  5,  3,  1;   1,  4,  9, 13, 13,  9,  4,  1;   1,  4,  9, 13, 13,  9,  4,  1;   1,  5, 14, 25, 30, 24, 12,  3;   1,  5, 15, 30, 42, 42, 30, 15,  5,  1;   1,  6, 21, 48, 75, 81, 60, 30, 10,  2; MATHEMATICA eptrees[n_]:=Prepend[Join@@Table[Tuples[eptrees/@y], {y, Rest[IntegerPartitions[n]]}], n]; eptrans[a_][n_]:=Sum[(-1)^Count[tree, _List, {0, Infinity}]*Product[a[i], {i, Flatten[{tree}]}], {tree, eptrees[n]}]; Table[DeleteCases[CoefficientList[-eptrans[-t&][n], t], 0], {n, 12}] CROSSREFS Cf. A220418, A273866, A289501, A290261, A290320. Sequence in context: A071017 A112049 A055230 * A112050 A283156 A298231 Adjacent sequences:  A290259 A290260 A290261 * A290263 A290264 A290265 KEYWORD tabf,nonn AUTHOR Gus Wiseman, Jul 24 2017 STATUS approved

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Last modified September 28 13:24 EDT 2020. Contains 337393 sequences. (Running on oeis4.)