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.

A265327 Smallest m such that A238324(m) = n.

Original entry on oeis.org

1, 4, 13, 2, 11, 42, 9, 40, 3, 38, 5, 36, 129, 34, 127, 32, 125, 30, 123, 28, 121, 6, 119, 8, 117, 10, 115, 12, 113, 14, 111, 16, 109, 392, 107, 390, 105, 388, 103, 386, 101, 384, 99, 382, 97, 380, 95, 378, 93, 376, 91, 374, 89, 372, 87, 370, 85, 368, 83
Offset: 1

Views

Author

Reinhard Zumkeller, Dec 07 2015

Keywords

Comments

A238324(a(n)) = n and A238324(m) != n for m < a(n).

Links

Crossrefs

Cf. A238324.

Programs

  • Haskell
    import Data.List (elemIndex); import Data.Maybe (fromJust)
a265327 = (+ 1) . fromJust . (`elemIndex` a238324_list)

A046901 a(n) = a(n-1) - n if a(n-1) > n, else a(n) = a(n-1) + n.

Original entry on oeis.org

1, 3, 6, 2, 7, 1, 8, 16, 7, 17, 6, 18, 5, 19, 4, 20, 3, 21, 2, 22, 1, 23, 46, 22, 47, 21, 48, 20, 49, 19, 50, 18, 51, 17, 52, 16, 53, 15, 54, 14, 55, 13, 56, 12, 57, 11, 58, 10, 59, 9, 60, 8, 61, 7, 62, 6, 63, 5, 64, 4, 65, 3, 66, 2, 67, 1, 68, 136, 67, 137
Offset: 1

Views

Author

N. J. A. Sloane

Keywords

Comments

Variation (1) on Recamán's sequence A005132.
a(A134931(n-1)) = 1. - Reinhard Zumkeller, Jan 31 2013

Links

Crossrefs

Cf. A008343, A008344, A005132.
Cf. A076039, A003462, A076041, A076042, A057198.
Cf. A085059.
Cf. A238324.

Programs

  • Haskell
    a046901 n = a046901_list !! (n-1)
a046901_list = scanl1 (\u v -> if u > v then u - v else u + v) [1..]
-- Reinhard Zumkeller, Dec 07 2015, Jan 31 2013
  • Maple
    A046901 := proc(n) option remember; if n = 1 then 1 else if A046901(n-1)>n then A046901(n-1)-n else A046901(n-1)+n; fi; fi; end;
  • Mathematica
    a[1]=1;a[n_]:=a[n]=If[a[n-1]>n,a[n-1]-n,a[n-1]+n]; Table[a[i],{i,70}]  (* Harvey P. Dale, Apr 01 2011 *)
nxt[{n_,a_}]:={n+1,If[a>n+1,a-n-1,a+n+1]}; NestList[nxt,{1,1},70][[All,2]] (* Harvey P. Dale, Jun 01 2019 *)
  • PARI
    a(n)=if(n<2,1,a(n-1)-if(sign(n-a(n-1))+1,-1,1)*n);

Formula

This is a concatenation S_0, S_1, S_2, ... where S_i = [b_0, b_1, ..., b_{k-1}], k=5*3^i, with b_0 = 1, b_{2j} = k+j, b_{2j+1} = (k+1)/2-j. E.g., S_0 = [1, 3, 6, 2, 7].
For any m>=1, for k such that 5*3^k+3>12m, a((5*3^k+3-12*m)/6)= m. For example, for k>=1, a((5*3^k-9)/6) = 1. - Benoit Cloitre, Oct 31 2002
a(n) = A008343(n+1) + 1. - Jon Maiga, Jul 09 2021
Showing 1-2 of 2 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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