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

 

Logo

Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A108994 Third diagonal of triangle A108990, in which the g.f. of row n, R_n(x), satisfies: [x^k] R_{n+1}(x) = [x^k] (1 + x*R_n(x))^(n+1) for k=0..n+1. 6
1, 3, 18, 180, 2670, 54096, 1411228, 45421776, 1747674405, 78485504845, 4037946005808, 234494393383614, 15187062546935643, 1086079262127563445, 85049134680670591560, 7241328591814507465712, 666283956766298002183275 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

a(n) is divisible by (n+1)*(n+2)/2.

LINKS

Table of n, a(n) for n=0..16.

FORMULA

a(n) = A108990(n+2, n) for n>=0. a(n) = (n+2)/2*A108995(n) for n>=0.

PROG

(PARI) {a(n)=local(F=1+x*O(x^n)); for(m=1, n+2, F=(1+x*F)^m); polcoeff(F, n)}

CROSSREFS

Cf. A108990, A108991, A108992, A108993, A108995, A108996.

Sequence in context: A223895 A111465 A247029 * A006472 A132853 A259666

Adjacent sequences:  A108991 A108992 A108993 * A108995 A108996 A108997

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jun 15 2005

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified December 11 15:43 EST 2017. Contains 295905 sequences.