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 A158825 Square array of coefficients in the successive iterations of x*C(x) = (1-sqrt(1-4*x))/2 where C(x) is the g.f. of the Catalan numbers (A000108); read by antidiagonals. 24
 1, 1, 1, 1, 2, 2, 1, 3, 6, 5, 1, 4, 12, 21, 14, 1, 5, 20, 54, 80, 42, 1, 6, 30, 110, 260, 322, 132, 1, 7, 42, 195, 640, 1310, 1348, 429, 1, 8, 56, 315, 1330, 3870, 6824, 5814, 1430, 1, 9, 72, 476, 2464, 9380, 24084, 36478, 25674, 4862, 1, 10, 90, 684, 4200, 19852, 67844 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,5 LINKS Paul D. Hanna, Table of n, a(n), n = 1..1275 (rows 1..50). FORMULA G.f. of column n = [g.f. of row n of A158830]/(1-x)^n. Row k equals the first column of the k-th matrix power of Catalan triangle A033184; thus triangle A033184 transforms row n into row n+1 of this array (A158825). [From Paul D. Hanna, Mar 30 2009] EXAMPLE Square array of coefficients in iterations of x*C(x) begins: 1,1,2,5,14,42,132,429,1430,4862,16796,58786,208012,742900,...; 1,2,6,21,80,322,1348,5814,25674,115566,528528,2449746,11485068,...; 1,3,12,54,260,1310,6824,36478,199094,1105478,6227712,35520498,...; 1,4,20,110,640,3870,24084,153306,993978,6544242,43652340,...; 1,5,30,195,1330,9380,67844,500619,3755156,28558484,219767968,...; 1,6,42,315,2464,19852,163576,1372196,11682348,100707972,...; 1,7,56,476,4200,38052,351792,3305484,31478628,303208212,...; 1,8,72,684,6720,67620,693048,7209036,75915708,807845676,...; 1,9,90,945,10230,113190,1273668,14528217,167607066,1952409954,...; 1,10,110,1265,14960,180510,2212188,27454218,344320262,...; 1,11,132,1650,21164,276562,3666520,49181418,666200106,...; 1,12,156,2106,29120,409682,5841836,84218134,1225314662,...; 1,13,182,2639,39130,589680,8999172,138755799,2157976392,...; 1,14,210,3255,51520,827960,13464752,221101608,3660331064,...; 1,15,240,3960,66640,1137640,19640032,342179672,6007747368,...; 1,16,272,4760,84864,1533672,28012464,516105720,9578580504,...; ... ILLUSTRATE ITERATIONS. Let G(x) = x*C(x), then the first few iterations of G(x) are: G(x) = x + x^2 + 2*x^3 + 5*x^4 + 14*x^5 + 42*x^6 + 132*x^7 +... G(G(x)) = x + 2*x^2 + 6*x^3 + 21*x^4 + 80*x^5 + 322*x^6 +... G(G(G(x))) = x + 3*x^2 + 12*x^3 + 54*x^4 + 260*x^5 +... G(G(G(G(x)))) = x + 4*x^2 + 20*x^3 + 110*x^4 + 640*x^5 +... ... RELATED TRIANGLES. The g.f. of column n is [g.f. of row n of A158830]/(1-x)^n where triangle A158830 begins: 1; 1,0; 2,0,0; 5,1,0,0; 14,10,0,0,0; 42,70,8,0,0,0; 132,424,160,4,0,0,0; 429,2382,1978,250,1,0,0,0; 1430,12804,19508,6276,302,0,0,0,0; 4862,66946,168608,106492,15674,298,0,0,0,0; 16796,343772,1337684,1445208,451948,33148,244,0,0,0,0; 58786,1744314,10003422,16974314,9459090,1614906,61806,162,0,0,0,0; ... Triangle A158835 transforms one diagonal into the next: 1; 1,1; 4,2,1; 27,11,3,1; 254,94,21,4,1; 3062,1072,217,34,5,1; 45052,15212,2904,412,50,6,1; 783151,257777,47337,6325,695,69,7,1; ... so that: A158835 * A158831 = A158832; A158835 * A158832 = A158833; A158835 * A158833 = A158834; where the diagonals start: A158831 = [1,1,6,54,640,9380,163576,3305484,...]; A158832 = [1,2,12,110,1330,19852,351792,7209036,...]; A158833 = [1,3,20,195,2464,38052,693048,14528217,...]; A158834 = [1,4,30,315,4200,67620,1273668,27454218,...]. MATHEMATICA nmax = 12; Clear[row]; row[n_] := row[n] = CoefficientList[Nest[(1-Sqrt[1-4#])/2&, x, n] + O[x]^(nmax+1), x] // Rest; T[n_, k_] := row[n][[k]]; Table[T[n-k+1, k], {n, 1, nmax}, {k, 1, n}] // Flatten (* Jean-François Alcover, Jul 13 2018, updated Aug 09 2018 *) PROG (PARI) {T(n, k)=local(F=serreverse(x-x^2+O(x^(k+2))), G=x); for(i=1, n, G=subst(F, x, G)); polcoeff(G, k)} CROSSREFS Cf. rows: A000108, A121988, A158826, A158827, A158828; antidiagonal sums: A158829. Cf. diagonals: A158831, A158832, A158833, A158834. Cf. related triangles: A158830, A158835, variant: A122888. Sequence in context: A098474 A153199 A056860 * A247507 A107111 A082037 Adjacent sequences:  A158822 A158823 A158824 * A158826 A158827 A158828 KEYWORD nonn,tabl AUTHOR Paul D. Hanna, Mar 28 2009, Mar 29 2009 STATUS approved

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Last modified January 22 04:27 EST 2020. Contains 331133 sequences. (Running on oeis4.)