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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A317790 a(n) = 2*a(n-1) - a(n-2) + a(n-4) - 2*(n-5) + a(n-6) for n>5, a(0)=a(1)=1, a(2)=a(3)=7, a(4)=13, a(5)=19. 1
 1, 1, 7, 7, 13, 19, 31, 37, 49, 61, 79, 91, 109, 127, 151, 169, 193, 217, 247, 271, 301, 331, 367, 397, 433, 469, 511, 547, 589, 631, 679, 721, 769, 817, 871, 919, 973, 1027, 1087, 1141, 1201, 1261, 1327, 1387, 1453, 1519, 1591, 1657, 1729, 1801, 1879, 1951 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS a(n) is b(2*n) in A215175. LINKS Colin Barker, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (2,-1,0,1,-2,1). FORMULA G.f.: (1 - x + 6*x^2 - 6*x^3 + 5*x^4 + x^5) / ((1 - x)^3*(1 + x)*(1 + x^2)). - Colin Barker, Aug 07 2018 a(n+1) = a(n) + 6*A059169(n+1). a(2*k+1) = A003215(k). From Bruno Berselli, Jul 08 2018: (Start) a(2*k) = A016921(A000982(k)). More generally: a(n) = (6*n^2 + 3*(3 - 2*(-1)^(n/2))*(1 + (-1)^n) + 2)/8. (End) MATHEMATICA CoefficientList[Series[(1 - x + 6 x^2 - 6 x^3 + 5 x^4 + x^5)/((1 - x)^3*(1 + x) (1 + x^2)), {x, 0, 51}], x] (* Michael De Vlieger, Aug 07 2018 *) Table[(6 n^2 + 3 (3 - 2 (-1)^(n/2)) (1 + (-1)^n) + 2)/8, {n, 0, 60}] (* Bruno Berselli, Aug 08 2018 *) PROG (PARI) Vec((1 - x + 6*x^2 - 6*x^3 + 5*x^4 + x^5) / ((1 - x)^3*(1 + x)*(1 + x^2)) + O(x^60)) \\ Colin Barker, Aug 07 2018 CROSSREFS Cf. A003215, A059169, A131729 (reverse order), A215175. Cf. A000982, A016921. Sequence in context: A072821 A038589 A332304 * A109539 A109541 A173314 Adjacent sequences: A317787 A317788 A317789 * A317791 A317792 A317793 KEYWORD nonn,easy AUTHOR Paul Curtz, Aug 07 2018 EXTENSIONS Incorrect term 837 replaced with 817 by Colin Barker, Aug 07 2018 More terms from Colin Barker, Aug 07 2018 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 February 4 05:49 EST 2023. Contains 360046 sequences. (Running on oeis4.)