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 1-3 of 3 results.

A249037 Number of even terms in first n terms of A249036.

Original entry on oeis.org

0, 1, 2, 2, 3, 4, 4, 4, 5, 5, 6, 7, 7, 7, 8, 9, 9, 9, 10, 10, 11, 11, 12, 13, 13, 13, 14, 15, 15, 15, 16, 17, 17, 17, 18, 19, 19, 19, 20, 20, 21, 21, 22, 22, 23, 23, 24, 25, 25, 25, 26, 27, 27, 27, 28, 29, 29, 29, 30, 31, 31, 31, 32, 33, 33, 33, 34, 35, 35, 35, 36, 37, 37, 37, 38, 39, 39, 39
Offset: 1

Views

Author

N. J. A. Sloane, Oct 26 2014

Keywords

Crossrefs

Cf. A249036, A249038.

Programs

A249038 Number of odd terms in first n terms of A249036.

Original entry on oeis.org

1, 1, 1, 2, 2, 2, 3, 4, 4, 5, 5, 5, 6, 7, 7, 7, 8, 9, 9, 10, 10, 11, 11, 11, 12, 13, 13, 13, 14, 15, 15, 15, 16, 17, 17, 17, 18, 19, 19, 20, 20, 21, 21, 22, 22, 23, 23, 23, 24, 25, 25, 25, 26, 27, 27, 27, 28, 29, 29, 29, 30, 31, 31, 31, 32, 33, 33, 33, 34, 35, 35, 35, 36, 37, 37, 37, 38, 39
Offset: 1

Views

Author

N. J. A. Sloane, Oct 26 2014

Keywords

Crossrefs

Cf. A249036, A249037.

Programs

A249039 a(1)=1, a(2)=2; thereafter a(n) = a(n-1) + a(n-1-(number of even terms so far)) + a(n-1-(number of odd terms so far)).

Original entry on oeis.org

1, 2, 4, 7, 11, 17, 26, 37, 52, 70, 92, 120, 157, 200, 254, 323, 401, 490, 597, 719, 859, 1021, 1211, 1438, 1687, 1979, 2325, 2740, 3183, 3704, 4262, 4863, 5553, 6350, 7201, 8174, 9216, 10336, 11545, 12894, 14350, 15928, 17646, 19526, 21596, 23893, 26352, 29060, 32060, 35406, 39167
Offset: 1

Views

Author

N. J. A. Sloane, Oct 26 2014

Keywords

Comments

Suggested by A006336, A007604 and A249036-A249038.

Links

Crossrefs

Cf. A006336, A007604, A249036, A249037, A249038.
A249040 and A249041 give numbers of even and odd terms so far.

Programs

  • Haskell
    import Data.List (genericIndex)
a249039 n = genericIndex a249039_list (n - 1)
a249039_list = 1 : 2 : f 2 2 1 1 where
   f x u v w = y : f (x + 1) y (v + 1 - mod y 2) (w + mod y 2)
               where y = u + a249039 (x - v) + a249039 (x - w)
-- Reinhard Zumkeller, Nov 11 2014
  • Maple
    M:=100;
v[1]:=1; v[2]:=2; w[1]:=0; w[2]:=1; x[1]:=1; x[2]:=1;
for n from 3 to M do
v[n]:=v[n-1]+v[n-1-w[n-1]]+v[n-1-x[n-1]];
if v[n] mod 2 = 0 then w[n]:=w[n-1]+1; x[n]:=x[n-1];
else w[n]:=w[n-1]; x[n]:=x[n-1]+1; fi;
od:
[seq(v[n], n=1..M)]; # A249039
[seq(w[n], n=1..M)]; # A249040
[seq(x[n], n=1..M)]; # A249041

Formula

For n > 1: a(n+1) = a(n) + a(n - A249040(n)) + a(n - A249041(n)) by mutual recursion. - Reinhard Zumkeller, Nov 11 2014
Showing 1-3 of 3 results.

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

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