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A121511 a(n) = a(n-1) + a(n-4) - a(n-5). 0
1, 5, 13, 25, 5, 9, 17, 29, 9, 13, 21, 33, 13, 17, 25, 37, 17, 21, 29, 41, 21, 25, 33, 45, 25, 29, 37, 49, 29, 33, 41, 53, 33, 37, 45, 57, 37, 41, 49, 61, 41, 45, 53, 65, 45, 49, 57, 69, 49, 53, 61, 73, 53, 57, 65, 77, 57, 61, 69, 81, 61, 65, 73, 85, 65, 69, 77 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
This sequence gives a linearly increasing triangle shaped form on plotting.
LINKS
FORMULA
G.f.: -x*(-1-4*x-8*x^2-12*x^3+21*x^4)/((1+x)*(x^2+1)*(x-1)^2).
a(n) = n + 17/2 + 7*(-1)^n/2 + A057077(n+1)*A010720(n-1).
PROG
(PARI) Vec(-x*(-1-4*x-8*x^2-12*x^3+21*x^4)/((1+x)*(x^2+1)*(x-1)^2) + O(x^75)) \\ Jinyuan Wang, Jun 07 2020
CROSSREFS
Cf. A001844.
Sequence in context: A340564 A140090 A271937 * A283750 A156679 A344813
KEYWORD
nonn,easy
AUTHOR
Roger L. Bagula, Sep 07 2006
EXTENSIONS
Definition replaced by recurrence - The Assoc. Editors of the OEIS, Oct 14 2009
More terms from Jinyuan Wang, Jun 07 2020
STATUS
approved

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Last modified July 18 18:59 EDT 2024. Contains 374388 sequences. (Running on oeis4.)