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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A027811 a(n) = 3*(n+1)*C(n+5,6). 0
6, 63, 336, 1260, 3780, 9702, 22176, 46332, 90090, 165165, 288288, 482664, 779688, 1220940, 1860480, 2767464, 4029102, 5753979, 8075760, 11157300, 15195180, 20424690, 27125280, 35626500, 46314450, 59638761, 76120128 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..27.

Index entries for linear recurrences with constant coefficients, signature (8,-28,56,-70,56,-28,8,-1).

FORMULA

Number of 12-subsequences of [ 1, n ] with just 5 contiguous pairs; g.f. 3*(2+5x)*x/(1-x)^8.

a(n) = C(n+1, 2)*C(n+5, 5). - Zerinvary Lajos, May 26 2005, corrected by R. J. Mathar, Feb 10 2016

CROSSREFS

Sequence in context: A222079 A158987 A055005 * A027950 A184447 A053700

Adjacent sequences:  A027808 A027809 A027810 * A027812 A027813 A027814

KEYWORD

nonn,easy

AUTHOR

thi ngoc dinh (via R. K. Guy)

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 10 11:12 EDT 2020. Contains 336379 sequences. (Running on oeis4.)