The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A257557 Expansion (x-1)/(x^5+2*x^3+2*x-1). 0
 1, 1, 2, 6, 14, 33, 79, 188, 448, 1068, 2545, 6065, 14454, 34446, 82090, 195633, 466223, 1111080, 2647872, 6310280, 15038353, 35838673, 85408986, 203542550, 485072726, 1156001777, 2754927327, 6565409092, 15646364288, 37287655956, 88862131873 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS FORMULA a(n) = Sum_{k=0..n} Sum_{i=0..(n-k)/2} C(2*k,i)*C(n-2*i-1,n-2*i-k). MATHEMATICA CoefficientList[Series[(x - 1)/(x^5 + 2 x^3 + 2 x - 1), {x, 0, 33}], x] (* Vincenzo Librandi, Apr 30 2015 *) PROG (Maxima) a(n):=sum(sum(binomial(2*k, i)*binomial(n-2*i-1, n-2*i-k), i, 0, (n-k)/2), k, 0, n); CROSSREFS Sequence in context: A089351 A005380 A309536 * A124612 A230439 A184697 Adjacent sequences:  A257554 A257555 A257556 * A257558 A257559 A257560 KEYWORD nonn AUTHOR Vladimir Kruchinin, Apr 29 2015 EXTENSIONS More terms from Vincenzo Librandi, Apr 30 2015 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified February 26 12:33 EST 2020. Contains 332279 sequences. (Running on oeis4.)