login
This site is supported by donations to The OEIS Foundation.
Logo

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A014402 Numbers found in denominators of expansion of Airy function Ai(x). 5
1, 1, 6, 12, 180, 504, 12960, 45360, 1710720, 7076160, 359251200, 1698278400, 109930867200, 580811212800, 46170964224000, 268334780313600, 25486372251648000, 161000868188160000, 17891433320656896000 (list; graph; refs; listen; history; internal format)
OFFSET

0,3

COMMENTS

Although the description is technically correct, this sequence is unsatisfactory because there are gaps in the series.

A014402 arises via Vandermonde determinants as in A203433; see the Mathematica section.  [From Clark Kimberling, Jan 02 2012]

LINKS

NIST's Digital Library of Mathematical Functions, Airy and Related Functions (Maclaurin Series) by Frank W. J. Olver.

FORMULA

a(2*n) = A176730(n). a(2*n + 1) = A176731(n). - Michael Somos, Oct 14 2011

EXAMPLE

Mathematica gives the series as 1/(3^(2/3)*Gamma(2/3)) - x/(3^(1/3)*Gamma(1/3)) + x^3/(6*3^(2/3)*Gamma(2/3)) - x^4/(12*3^(1/3)*Gamma(1/3) + x^6/(180*3^(2/3)*Gamma(2/3) - x^7/(504*3^(1/3)*Gamma(1/3) + x^9/(12960*3^(2/3)*Gamma(2/3) - ...

MATHEMATICA

Series[ AiryAi[ x ], {x, 0, 30} ]

a[ n_] := If[ n<0, 0, (n + Quotient[ n, 2])! / Product[ 3 k + 1 + Mod[n, 2], {k, 0, Quotient[ n, 2] - 1}]] (* Michael Somos, Oct 14 2011 *)

(* Next, A014402 generated in via Vandermonde determinants based on A007494 *)

f[j_] := j + Floor[(j + 1)/2]; z = 18;

v[n_] := Product[Product[f[k] - f[j], {j, 1, k - 1}], {k, 2, n}]

d[n_] := Product[(i - 1)!, {i, 1, n}]

Table[v[n], {n, 1, z}]              (* A203433 *)

Table[v[n + 1]/v[n], {n, 1, z - 1}] (* A014402 *)

Table[v[n]/d[n], {n, 1, 20}]        (* A203434 *)

(* Clark Kimberling, Jan 02 2012 *)

PROG

(PARI) {a(n) = if( n<0, 0, (n\2 + n)! / prod( k=0, n\2 -1, n%2 + 3*k + 1))} /* Michael Somos, Oct 14 2011 */

CROSSREFS

Cf. A014403, A176730, A176731, A060507.

Sequence in context: A070020 A203754 A002922 * A181493 A051784 A158046

Adjacent sequences:  A014399 A014400 A014401 * A014403 A014404 A014405

KEYWORD

nonn

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
Recent Additions | More pages | Superseeker | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .

Last modified February 16 11:25 EST 2012. Contains 205907 sequences.