The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A027005 a(n) = T(2*n+1,n+2), T given by A026998. 1
1, 19, 101, 370, 1148, 3278, 8967, 23993, 63483, 167040, 438346, 1148844, 3009181, 7879855, 20631713, 54016798, 141420392, 370246298, 969320643, 2537718005, 6643835991, 17393792844, 45537545686, 119218847640, 312119000953, 817138159243, 2139295481117 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Bisection of A027963.
LINKS
FORMULA
From Colin Barker, Feb 19 2016: (Start)
a(n) = (-6+(2^(-1-n)*((3-sqrt(5))^n*(-25+11*sqrt(5)) + (3+sqrt(5))^n*(25+11*sqrt(5))))/sqrt(5) + 7*(1+n) - 6*(1+n)*(2+n)).
a(n) = 6*a(n-1)-13*a(n-2)+13*a(n-3)-6*a(n-4)+a(n-5) for n>5.
G.f.: x*(1+13*x-2*x^3) / ((1-x)^3*(1-3*x+x^2)).
(End)
MATHEMATICA
LinearRecurrence[{6, -13, 13, -6, 1}, {1, 19, 101, 370, 1148}, 30] (* Harvey P. Dale, Aug 19 2020 *)
PROG
(PARI) Vec(x*(1+13*x-2*x^3)/((1-x)^3*(1-3*x+x^2)) + O(x^40)) \\ Colin Barker, Feb 19 2016
CROSSREFS
Cf. A027963.
Sequence in context: A044651 A287303 A142216 * A061696 A062643 A245528
KEYWORD
nonn,easy
AUTHOR
STATUS
approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 20 19:00 EDT 2024. Contains 372720 sequences. (Running on oeis4.)