This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A140107 a(n) = binomial(n+3, 3)*7^n. 7
 1, 28, 490, 6860, 84035, 941192, 9882516, 98825160, 951192165, 8877793540, 80787921214, 719746934452, 6297785676455, 54257845827920, 461191689537320, 3874010192113488, 32202709721943369, 265198785945415980 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS With a different offset, number of n-permutations (n=4) of 8 objects: s, t, u, v, w, z, x, y with repetition allowed, containing exactly three u's. uuus, uusu, usuu, suuu, uuut, uutu, utuu, tuuu, uuuv, uuvu, uvuu, vuuu, uuuw, uuwu, uwuu, wuuu, uuuz, uuzu, uzuu, zuuu, uuux, uuxu, uxuu, xuuu, uuuy, uuyu, uyuu, yuuu LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..400 Index entries for linear recurrences with constant coefficients, signature (28, -294, 1372, -2401). FORMULA From R. J. Mathar, Jun 03 2009: (Start) a(n) = 28*a(n-1) - 294*a(n-2) + 1372*a(n-3) - 2401*a(n-4). G.f.: 1/(7*x-1)^4. (End) MAPLE seq(binomial(n+3, 3)*7^n, n=0..26); MATHEMATICA Table[Binomial[n+3, 3]7^n, {n, 0, 20}] (* or *) LinearRecurrence[{28, -294, 1372, -2401}, {1, 28, 490, 6860}, 20] (* Harvey P. Dale, Jun 21 2016 *) PROG (Sage) [lucas_number2(n, 7, 0)*binomial(n, 3)/7^3for n in xrange(3, 21)] # Zerinvary Lajos, Mar 13 2009 (MAGMA) [7^n* Binomial(n+3, 3): n in [0..20]]; // Vincenzo Librandi, Oct 12 2011 (PARI) a(n)=binomial(n+3, 3)*7^n \\ Charles R Greathouse IV, Oct 07 2015 CROSSREFS Sequence in context: A223997 A263949 A240463 * A028170 A211677 A076172 Adjacent sequences:  A140104 A140105 A140106 * A140108 A140109 A140110 KEYWORD nonn,easy AUTHOR Zerinvary Lajos, Jun 03 2008 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 May 25 19:58 EDT 2019. Contains 323576 sequences. (Running on oeis4.)