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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

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Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)