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!)
 A032793 Numbers that are congruent to {1, 2, 4} mod 5. 28
 1, 2, 4, 6, 7, 9, 11, 12, 14, 16, 17, 19, 21, 22, 24, 26, 27, 29, 31, 32, 34, 36, 37, 39, 41, 42, 44, 46, 47, 49, 51, 52, 54, 56, 57, 59, 61, 62, 64, 66, 67, 69, 71, 72, 74, 76, 77, 79, 81, 82, 84, 86, 87, 89, 91, 92, 94, 96, 97, 99, 101, 102, 104, 106, 107, 109 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Guenther Schrack, Table of n, a(n) for n = 1..10000 Index entries for linear recurrences with constant coefficients, signature (1,0,1,-1). FORMULA a(n) = a(n-1) + a(n-3) - a(n-4) for n>4. a(n) = -1 + Sum_{k=1..n} ((1/9)*(2*(k mod 3) + 8*((k+1) mod 3) + 5*((k+2) mod 3)), with n >= 1. - Paolo P. Lava, Sep 03 2010 a(n) = floor((5*n-2)/3). - Gary Detlefs, May 14 2011 G.f.: x*(1+x+2*x^2+x^3)/((1+x+x^2)*(1-x)^2). - R. J. Mathar, Oct 08 2011 From Wesley Ivan Hurt, Jun 14 2016: (Start) a(n) = (15*n - 9 + 2*sqrt(3)*sin(2*n*Pi/3))/9. a(3k) = 5k - 1, a(3k-1) = 5k - 3, a(3k-2) = 5k - 4. (End) E.g.f.: (9 + 3*(5*x - 3)*exp(x) + 2*sqrt(3)*sin(sqrt(3)*x/2)*(cosh(x/2) - sinh(x/2)))/9. - Ilya Gutkovskiy, Jun 14 2016 From Guenther Schrack, Oct 31 2019: (Start) a(n) = a(n-3) + 5 with a(1) = 1, a(2) = 2, a(3) = 4 for n > 3. a(n) = (15*n - 9 + (w^(2*n) - w^n)*(1 + 2*w))/9 where w = (-1 + sqrt(-3))/2. (End) MAPLE A032793:=n->(15*n-9+2*sqrt(3)*sin(2*n*Pi/3))/9: seq(A032793(n), n=1..100); # Wesley Ivan Hurt, Jun 14 2016 MATHEMATICA Select[Range[0, 200], MemberQ[{1, 2, 4}, Mod[#, 5]] &] (* Vladimir Joseph Stephan Orlovsky, Feb 11 2012 *) LinearRecurrence[{1, 0, 1, -1}, {1, 2, 4, 6}, 90] (* Harvey P. Dale, May 20 2019 *) PROG (MAGMA)[ n: n in [0..120] | n mod 5 in {1, 2, 4} ]; // Vincenzo Librandi, Dec 29 2010 (PARI) a(n)=n\3*5+[-1, 1, 2][n%3+1] \\ Charles R Greathouse IV, Jan 18 2012 (Sage) [(15*n - 9 + 2*sqrt(3)*sin(2*n*pi/3))/9 for n in (1..100)] # G. C. Greubel, Nov 06 2019 (GAP) a:=[1, 2, 4, 6];; for n in [5..100] do a[n]:=a[n-1]+a[n-3]-a[n-4]; od; a; # G. C. Greubel, Nov 06 2019 CROSSREFS Cf. A032794, A032795. Sequence in context: A186151 A184732 A039009 * A195127 A292654 A083088 Adjacent sequences:  A032790 A032791 A032792 * A032794 A032795 A032796 KEYWORD nonn,easy AUTHOR Patrick De Geest, May 15 1998 EXTENSIONS Better description from Michael Somos, Jun 08 2000 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 21 19:02 EST 2020. Contains 332109 sequences. (Running on oeis4.)