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.

A008353 2^n*(2^(n+1) - n - 1).

Original entry on oeis.org

1, 4, 20, 96, 432, 1856, 7744, 31744, 128768, 519168, 2085888, 8364032, 33501184, 134103040, 536625152, 2146959360, 8588820480, 34357379072, 137433972736, 549745328128, 2199001235456, 8796046884864, 35184275619840, 140737287028736, 562949533990912
Offset: 0

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Author

Keywords

Crossrefs

a(n) = A066345(2*n+1).
a(n) = 1 for n=0, 4 * A008464(n-2) else.

Programs

  • Magma
    [2^n*(2^(n+1) - n - 1): n in [0..50]]; // Vincenzo Librandi, Apr 25 2011
    
  • PARI
    Vec(-(8*x^2-4*x+1)/((2*x-1)^2*(4*x-1)) + O(x^100)) \\ Colin Barker, Feb 26 2015

Formula

a(n) = sum{k=0..n+1, C(2n+2, 2k)-2k(n-k+1)*C(n+1, k)/n}, n>0. - Paul Barry, Feb 24 2005
a(n) = 8*a(n-1)-20*a(n-2)+16*a(n-3). - Colin Barker, Feb 26 2015
G.f.: -(8*x^2-4*x+1) / ((2*x-1)^2*(4*x-1)). - Colin Barker, Feb 26 2015

A066346 Number of winning binary "same game" templates with ternary digits totaling n.

Original entry on oeis.org

1, 0, 1, 0, 2, 2, 4, 9, 13, 28, 46, 84, 146, 252, 433, 736, 1242, 2087, 3482, 5791, 9587, 15823, 26038, 42743, 70016, 114485, 186903, 304728, 496260, 807395, 1312504, 2132102, 3461407, 5616609, 9109732
Offset: 0

Views

Author

Frank Ellermann, Dec 23 2001

Keywords

Comments

Equivalently, templates whose minimum matching string has length n.

Examples

			a(1)..a(5) correspond to the winning templates -;2;-; 121,22; 122,221.
a(6) = 4 winning templates 11211,1212,2121 and 222 have a total of 6.
		

Crossrefs

Cf. A066345 (definition), A007931 (templates). A035615 (binary same game).

Extensions

a(17)-a(35) from Sean A. Irvine, Oct 09 2023

A066709 Triangle T(r,c) of winning binary "same game" templates.

Original entry on oeis.org

1, 0, 1, 1, 2, 1, 0, 2, 4, 1, 1, 5, 8, 5, 1, 0, 3, 14, 15, 6, 1, 1, 9, 25, 32, 21, 7, 1, 0, 4, 32, 62, 56, 28, 8, 1, 1, 14, 56, 109, 122, 84, 36, 9, 1, 0, 5, 60, 170, 242, 210, 120, 45, 10, 1, 1, 20, 105, 275, 436, 457, 330, 165, 55, 11, 1, 0, 6, 100, 375, 732, 912, 792, 495, 220, 66, 12, 1
Offset: 1

Views

Author

Frank Ellermann, Dec 31 2001

Keywords

Comments

T(r,c) is the number of winning templates with length r and minimum matching string length c; equivalently, ternary digits totaling r+c. For a definition and row sums 1,1,4,7,20, etc. see A066345. For antidiagonal sums 1,0,2,2,4,9, etc. see A066346.

Examples

			Rows:
1;
0,1;
1,2,1;
0,2,4,1;
1,5,8,5,1;
0,3,14,15,6,1; ...
a(17) = T(6,2) = 3 winning templates with length 6 and total 8 = 6+2: 211211, 121121, 112112.
A035615(6) = 2*( 1*1+0*1+1*3+1*1+2*2+1*1+1*1+0*1+2*1+1*1 ) = 2*13 = 26.
		

Crossrefs

Formula

A035615(n) = 2 * Sum_{r=1..n-1, c=1..min(r,n-r)} T(r,c) * P(n-r,c) where P(n-r,c) = C(n-r-1,c-1) = (n-r-1)!/((n-r-c-2)!*(c-1)!).

Extensions

More terms from Sean A. Irvine, Nov 03 2023
Showing 1-3 of 3 results.