cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-2 of 2 results.

A103378 a(n) = a(n-10) + a(n-11) for n > 11, and a(n) = 1 for 1 <= n <= 11.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 7, 8, 8, 8, 8, 8, 8, 8, 8, 9, 12, 15, 16, 16, 16, 16, 16, 16, 16, 17, 21, 27, 31, 32, 32, 32, 32, 32, 32, 33, 38, 48, 58, 63, 64, 64, 64, 64, 64, 65, 71, 86, 106, 121, 127, 128
Offset: 1

Views

Author

Jonathan Vos Post, Feb 15 2005

Keywords

Examples

			a(52)=17 because a(52)=a(52-10)+a(52-11) = a(42)+a(41) = 9 + 8.
		

Crossrefs

Programs

  • Maple
    A103378 := proc(n) option remember; if n <= 11 then 1 ; else A103378(n-10)+A103378(n-11) ; fi ; end: seq(A103378(n),n=1..78) ; # R. J. Mathar, Nov 22 2007
  • Mathematica
    k=10; Do[a[n]=1, {n, k+1}]; a[n_]:=a[n]=a[n-k]+a[n-k-1]; A103377=Array[a, 100] N[Solve[x^10 - x - 1 == 0, x], 111][[2]]
    LinearRecurrence[Join[Table[0,{9}],{1,1}],Table[1,{11}],80] (* Harvey P. Dale, Aug 14 2013 *)
  • PARI
    Vec((x^10-1)/(x-1)/(1-x^10-x^11)+O(x^80)) \\ M. F. Hasler, Sep 19 2015

Formula

G.f.: x*(1+x+x^2+x^3+x^4+x^5+x^6+x^7+x^8+x^9)/(1-x^10-x^11). - R. J. Mathar, Nov 22 2007

Extensions

Corrected and extended by R. J. Mathar, Nov 22 2007
Edited by M. F. Hasler, Sep 19 2015

A103398 Semiprimes in A103378.

Original entry on oeis.org

4, 9, 15, 21, 33, 38, 58, 65, 86, 106, 121, 129, 265, 511, 2047, 2049, 4109, 16293, 16489, 17855, 19857, 32678, 34709, 66217, 104739, 220918, 240367, 262298, 293323, 954413, 2082999, 3145729, 3498467, 4296813, 16442015, 18037939, 21317326
Offset: 1

Views

Author

Jonathan Vos Post, Feb 15 2005

Keywords

Crossrefs

Programs

  • Maple
    A103378 := proc(n) option remember; if n <= 11 then 1 ; else procname(n-10)+procname(n-11) ; fi ; end proc:
    a78prev := -1 ; for n from 1 to 400 do a78 := A103378(n) ; if numtheory[bigomega](a78) = 2 and a78 <> a78prev then printf("%d,",a78) ; end if; a78prev := a78 ; end do: # R. J. Mathar, Jun 11 2010
  • Mathematica
    SemiprimeQ[n_]:=Plus@@FactorInteger[n][[All, 2]]?2; Clear[a]; k=10; Do[a[n]=1, {n, k+1}]; a[n_]:=a[n]=a[n-k]+a[n-k-1]; A103377=Array[a, 100] A103387=Union[Select[Array[a, 1000], PrimeQ]] A103397=Union[Select[Array[a, 300], SemiprimeQ]] N[Solve[x^11 - x - 1 == 0, x], 111][[2]] (* Ray Chandler and Robert G. Wilson v *)

Formula

Intersection of A103378 with A001358.

Extensions

Edited and extended by Ray Chandler and Robert G. Wilson v
Entries >511 corrected by R. J. Mathar, Jun 11 2010
Showing 1-2 of 2 results.