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.

A158303 Triangle read by rows, A007318 * (A158300 * 0^(n-k)).

Original entry on oeis.org

1, 1, 2, 1, 4, 2, 1, 6, 6, 8, 1, 8, 12, 32, 8, 1, 10, 20, 80, 40, 32, 1, 12, 30, 160, 120, 192, 32, 1, 14, 42, 280, 280, 672, 224, 128, 1, 16, 56, 448, 560, 1792, 896, 1024, 128, 1, 18, 72, 672, 1008, 4032, 2688, 4608, 1152, 512
Offset: 0

Views

Author

Gary W. Adamson, Mar 15 2009

Keywords

Examples

			First few rows of the triangle =
1;
1, 2;
1, 4, 2;
1, 6, 6, 8;
1, 8, 12, 32, 8;
1, 10, 20, 80, 40, 32;
1, 12, 30, 160, 120, 192, 32;
1, 14, 42, 280, 280, 672, 224, 128;
1, 16, 56, 448, 560, 1792, 896, 1024, 128;
1, 18, 72, 672, 1008, 4032, 2688, 4608, 1152, 512;
1, 20, 90, 960, 1680, 8064, 6720, 15360, 5760, 5120, 512;
...
		

Crossrefs

Cf. A158300, A122983 (row sums), A054879, A066443

Formula

Triangle read by rows, A007318 * (A158300 * 0^(n-k)). Equals binomial transform of an infinite lower triangular matrix with A158300: (1, 2, 2, 8, 8, 32, 32,...) as the main diagonal and the rest zeros.

A158302 "1" followed by repeats of 2^k deleting all 4^k, k>0.

Original entry on oeis.org

1, 2, 2, 8, 8, 32, 32, 128, 128, 512, 512, 2048, 2048, 8192, 8192, 32768, 32768, 131072, 131072, 524288, 524288, 2097152, 2097152, 8388608, 8388608, 33554432, 33554432, 134217728, 134217728, 536870912, 536870912, 2147483648, 2147483648, 8589934592
Offset: 0

Views

Author

Gary W. Adamson, Mar 15 2009

Keywords

Comments

Binomial transform = A122983: (1, 3, 7, 21, 61, 183,...). Equals right border of triangle A158301.
Also the order of the graph automorphism group of the n+1 X n+1 black bishop graph. - Eric W. Weisstein, Jun 27 2017
For n > 1, also the order of the graph automorphism group of the n X n white bishop graph. - Eric W. Weisstein, Jun 27 2017

Examples

			Given "1" followed by repeats of powers of 2: (1, 2, 2, 4, 4, 8, 8, 16, 16,...);
delete powers of 4: (4, 16, 64, 156,...) leaving A158300:
(1, 2, 2, 8, 8, 32, 32, 128, 128,...).
		

Crossrefs

Programs

  • Maple
    1,seq(4^floor((n+1)/2)/2, n=1..33); # Peter Luschny, Jul 02 2020
  • Mathematica
    Join[{1}, Flatten[Table[{2^n, 2^n}, {n, 1, 41, 2}]]] (* Harvey P. Dale, Jan 24 2013 *)
    Join[{1}, Table[2^(2 Ceiling[n/2] - 1), {n, 20}]] (* Eric W. Weisstein, Jun 27 2017 *)
    Join[{1}, 2^(2 Ceiling[Range[20]/2] - 1)] (* Eric W. Weisstein, Jun 27 2017 *)

Formula

1 followed by repeats of powers of 2, deleting powers of 4: (4, 16, 64,...). Inverse binomial transform of A122983 starting (1, 3, 7, 21, 61, 183,...).
For n > 3: a(n) = a(n-1)*a(n-2)/a(n-3). [Reinhard Zumkeller, Mar 06 2011]
For n > 3: a(n) = 4a(n-2). [Charles R Greathouse IV, Feb 06 2011]
a(n) = Sum_{k, 0<=k<=n} A154388(n,k)*2^k. - Philippe Deléham, Dec 17 2011
G.f.: (1+2*x-2*x^2)/(1-4*x^2). - Philippe Deléham, Dec 17 2011

Extensions

More terms from Harvey P. Dale, Jan 24 2013

A158301 Denominator of Bernoulli(n, -5/6).

Original entry on oeis.org

1, 3, 36, 27, 6480, 972, 326592, 34992, 8398080, 1259712, 665127936, 45349632, 990435962880, 1632586752, 78364164096, 58773123072, 239794342133760, 2115832430592, 13507474236899328, 76169967501312, 201088714203463680
Offset: 0

Views

Author

N. J. A. Sloane, Nov 08 2009

Keywords

Crossrefs

For numerators see A158300.

Programs

  • Mathematica
    Table[Denominator[BernoulliB[n, -5/6]], {n, 0, 50}] (* Vincenzo Librandi, Mar 19 2014 *)
Showing 1-3 of 3 results.