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.

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A296690 a(1) = a(2) = a(3) = 2, a(4) = 4, a(5) = a(6) = 5; a(n) = a(n-a(n-1)) + a(n-a(n-2)) + a(n-a(n-3)) for n > 6.

Original entry on oeis.org

2, 2, 2, 4, 5, 5, 6, 6, 8, 10, 9, 8, 11, 12, 12, 13, 14, 14, 15, 15, 16, 17, 17, 18, 18, 20, 22, 21, 20, 24, 25, 20, 25, 28, 28, 21, 29, 32, 30, 25, 30, 30, 36, 30, 32, 35, 34, 36, 35, 37, 37, 38, 38, 40, 40, 40, 42, 41, 43, 43, 43, 45, 44, 46, 46, 47, 47, 49, 49, 49, 51, 50, 52, 52, 52, 54, 53, 56, 55, 58, 55, 62, 55
Offset: 1

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Author

Altug Alkan, Dec 18 2017

Keywords

Crossrefs

Programs

  • Maple
    a:= proc(n) option remember; procname(n-procname(n-1))+procname(n-procname(n-2))+procname(n-procname(n-3)) end proc:
    a(1):= 2: a(2):= 2: a(3):= 2: a(4):= 4: a(5):= 5: a(6):= 5:
    map(a, [$1..100]); #  after Robert Israel at A296440
  • Mathematica
    a[n_] := a[n] = If[n<7, {2, 2, 2, 4, 5, 5}[[n]], a[n - a[n-1]] + a[n - a[n-2]] + a[n - a[n-3]]]; Array[a, 100] (* after Giovanni Resta at A296440 *)
  • PARI
    q=vector(10^5); q[1]=2; q[2]=2; q[3]=2; q[4]=4; q[5]=5; q[6]=5; for(n=7, #q, q[n] = q[n-q[n-1]]+q[n-q[n-2]]+q[n-q[n-3]]); q
    
  • Scheme
    (definec (A296690 n) (cond ((<= n 3) 2) ((<= n 5) n) ((= n 6) 5) (else (+ (A296690 (- n (A296690 (- n 1)))) (A296690 (- n (A296690 (- n 2)))) (A296690 (- n (A296690 (- n 3)))))))) ;; Antti Karttunen, Dec 18 2017
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