A093175 Tetranacci numbers starting with first four squares.

1, 4, 9, 16, 30, 59, 114, 219, 422, 814, 1569, 3024, 5829, 11236, 21658, 41747, 80470, 155111, 298986, 576314, 1110881, 2141292, 4127473, 7955960, 15335606, 29560331, 56979370, 109831267, 211706574, 408077542, 786594753, 1516210136, 2922589005

Offset

1,2

Links

Table of n, a(n) for n=1..33.

Index entries for linear recurrences with constant coefficients, signature (1, 1, 1, 1).

Formula

a(n) = a(n-1) + a(n-2) + a(n-3) + a(n-4).

G.f.: -x*(1+x)*(2*x^2+2*x+1)/(-1+x+x^2+x^3+x^4). a(n)=2*A000078(n+3)+2*A000078(n)-A001631(n+1). [R. J. Mathar, Apr 20 2009]

Mathematica

a[1] = 1; a[2] = 4; a[3] = 9; a[4] = 16; a[n_] := a[n] = a[n - 1] + a[n - 2] + a[n - 3] + a[n - 4]; Table[ a[n], {n, 33}] (* Robert G. Wilson v *)
LinearRecurrence[{1, 1, 1, 1}, Range[4]^2, 40] (* Harvey P. Dale, Oct 16 2012 *)

Crossrefs

Cf. A086192.

Sequence in context: A001640 A161328 A073141 * A138992 A199936 A326958

Adjacent sequences: A093172 A093173 A093174 * A093176 A093177 A093178

Keyword

nonn

Author

Jun Mizuki (suzuki32(AT)sanken.osaka-u.ac.jp), May 11 2004

Extensions

More terms from Robert G. Wilson v and Labos Elemer, May 12 2004, May 11 2004

Status

approved