OFFSET
1,3
REFERENCES
Jay Kappraff, Beyond Measure, A Guided Tour Through Nature, Myth and Number, World Scientific, 2002.
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (2, 25).
FORMULA
a(n) = 2*a(n-1) + 25*a(n-2).
a(n+1) = ((1+sqrt(26))^n - (1-sqrt(26))^n)/(2*sqrt(26)). - Rolf Pleisch, Jul 06 2009
a(n) = (5*i)^(n-2)*ChebyshevU(n-2, -i/5). - G. C. Greubel, Jul 12 2021
MATHEMATICA
Rest@CoefficientList[Series[x^2/(1 -2*x -25*x^2), {x, 0, 40}], x]
Join[{a=0, b=1}, Table[c=2*b+25*a; a=b; b=c, {n, 60}]] (* Vladimir Joseph Stephan Orlovsky, Feb 01 2011 *)
PROG
(Magma) [n le 2 select n-1 else 2*Self(n-1) +25*Self(n-2): n in [1..30]]; // G. C. Greubel, Jul 12 2021
(Sage) [(5*i)^(n-2)*chebyshev_U(n-2, -i/5) for n in [1..30]] # G. C. Greubel, Jul 12 2021
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Roger L. Bagula and Gary W. Adamson, Sep 23 2006
EXTENSIONS
Definition replaced by generating function - the Assoc. Eds. of the OEIS, Mar 27 2010
STATUS
approved