This site is supported by donations to The OEIS Foundation.

 Annual Appeal: Please make a donation to keep the OEIS running. In 2018 we replaced the server with a faster one, added 20000 new sequences, and reached 7000 citations (often saying "discovered thanks to the OEIS"). Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A125301 a(3n) = n, a(3n+1) = (n+2)*a(3n), a(3n+2) = (n+2)*a(3n+1). 1
 0, 0, 0, 1, 3, 9, 2, 8, 32, 3, 15, 75, 4, 24, 144, 5, 35, 245, 6, 48, 384, 7, 63, 567, 8, 80, 800, 9, 99, 1089, 10, 120, 1440, 11, 143, 1859, 12, 168, 2352, 13, 195, 2925, 14, 224, 3584, 15, 255, 4335, 16, 288, 5184, 17, 323, 6137, 18, 360, 7200, 19, 399, 8379, 20 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 COMMENTS From a competency test. LINKS Colin Barker, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (0,0,4,0,0,-6,0,0,4,0,0,-1). FORMULA From Colin Barker, Jan 24 2017: (Start) a(n) = 4*a(n-3) - 6*a(n-6) + 4*a(n-9) - a(n-12) for n>11. G.f.: x^3*(1 + 3*x + 9*x^2 - 2*x^3 - 4*x^4 - 4*x^5 + x^6 + x^7 + x^8) / ((1 - x)^4*(1 + x + x^2)^4). (End) MAPLE a:=proc(n): if n mod 3=0 then n/3 elif n mod 3 = 1 then (n+5)*a(n-1)/3 else (n+4)*a(n-1)/3 fi end: seq(a(n), n=0..75); # Emeric Deutsch, Jan 01 2007 MATHEMATICA LinearRecurrence[{0, 0, 4, 0, 0, -6, 0, 0, 4, 0, 0, -1}, {0, 0, 0, 1, 3, 9, 2, 8, 32, 3, 15, 75}, 70] (* Harvey P. Dale, Jul 31 2018 *) PROG (PARI) concat(vector(3), Vec(x^3*(1 + 3*x + 9*x^2 - 2*x^3 - 4*x^4 - 4*x^5 + x^6 + x^7 + x^8) / ((1 - x)^4*(1 + x + x^2)^4) + O(x^100))) \\ Colin Barker, Jan 24 2017 CROSSREFS Sequence in context: A094724 A008564 A060956 * A263559 A262343 A140985 Adjacent sequences:  A125298 A125299 A125300 * A125302 A125303 A125304 KEYWORD nonn,easy AUTHOR Trent Stratton (trent.stratton(AT)gov.bc.ca), Dec 08 2006 EXTENSIONS Solution from N. J. A. Sloane, Dec 08 2006 More terms from Emeric Deutsch, Jan 01 2007 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 December 14 08:07 EST 2018. Contains 318090 sequences. (Running on oeis4.)