The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A107240 Sum of squares of first n tribonacci numbers (A000213). 4
 1, 2, 3, 12, 37, 118, 407, 1368, 4617, 15642, 52891, 178916, 605325, 2047726, 6927407, 23435376, 79281105, 268206130, 907335091, 3069492092, 10384017717, 35128880742, 118840150983, 402033352264, 1360069089113, 4601080768074 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Harvey P. Dale, Table of n, a(n) for n = 1..1000 M. Feinberg, Fibonacci-Tribonacci, Fib. Quart. 1(3) (1963), 71-74. Eric Weisstein's World of Mathematics, Tribonacci Number. Index entries for linear recurrences with constant coefficients, signature (3, 1, 3, -7, 1, -1, 1). FORMULA a(n) = Sum_{i=1..n} A000213(i)^2. a(n)= 3*a(n-1) +a(n-2) +3*a(n-3) -7*a(n-4) +a(n-5) -a(n-6) +a(n-7). G.f.: (x^3-x^2+3*x-1)*(1+x)^2/((x-1)*(x^3+x^2+3*x-1)*(x^3-x^2-x-1)). - R. J. Mathar, Aug 11 2009 EXAMPLE a(6) = 1^2 + 1^2 + 1^2 + 3^2 + 5^2 + 9^2 = 118. MATHEMATICA Accumulate[LinearRecurrence[{1, 1, 1}, {1, 1, 1}, 30]^2] (* Harvey P. Dale, Nov 11 2011 *) LinearRecurrence[{3, 1, 3, -7, 1, -1, 1}, {1, 2, 3, 12, 37, 118, 407}, 26] (* Ray Chandler, Aug 02 2015 *) CROSSREFS Cf. A000213, A001654, A107239, A107241-A107247. Sequence in context: A072440 A135522 A353831 * A099171 A268561 A352099 Adjacent sequences:  A107237 A107238 A107239 * A107241 A107242 A107243 KEYWORD easy,nonn AUTHOR Jonathan Vos Post, May 14 2005 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.

Last modified July 7 02:44 EDT 2022. Contains 355141 sequences. (Running on oeis4.)