The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A249060 Column 1 of the triangular array at A249057. 3
 1, 4, 5, 24, 35, 192, 315, 1920, 3465, 23040, 45045, 322560, 675675, 5160960, 11486475, 92897280, 218243025, 1857945600, 4583103525, 40874803200, 105411381075, 980995276800, 2635284526875, 25505877196800, 71152682225625, 714164561510400, 2063427784543125 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS For n > 2, if n is even, a(n)/[(n+1)*(n-1)*(n-3)*...*7*5] = n + 3 and if n is odd, a(n)/[(n+1)*(n-1)*(n-3)*...*6*4] = n + 3. - Derek Orr, Oct 21 2014 LINKS Clark Kimberling, Table of n, a(n) for n = 0..100 FORMULA a(2*n) = (2*n+3)*(2*n+1)!!/3, for n > 0. - Derek Orr, Oct 21 2014 a(2*n+1) = (n+2)!*2^(n+1), for n > 0. - Derek Orr, Oct 21 2014 a(n) = gcd_2((n+3)!,(n+3)!!), where gcd_2(b,c) denotes the second-largest common divisor of non-coprime integers b and c, as defined in A309491. - Lechoslaw Ratajczak, Apr 15 2021 EXAMPLE First 3 rows from A249057: 1 4    1 5    4    1, so that a(0) = 1, a(1) = 4, a(2) = 5. MATHEMATICA z = 30; p[x_, n_] := x + (n + 2)/p[x, n - 1]; p[x_, 1] = 1; t = Table[Factor[p[x, n]], {n, 1, z}]; u = Numerator[t]; v1 = Flatten[CoefficientList[u, x]]; (* A249057  *) v2 = u /. x -> 1  (* A249059 *) v3 = u /. x -> 0  (* A249060 *) CROSSREFS Cf. A249057, A249060. Sequence in context: A042123 A041531 A089499 * A042601 A219515 A248246 Adjacent sequences:  A249057 A249058 A249059 * A249061 A249062 A249063 KEYWORD nonn,easy,changed AUTHOR Clark Kimberling, Oct 20 2014 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 15 20:23 EDT 2021. Contains 343920 sequences. (Running on oeis4.)