A028400 -id:A028400 - cp's OEIS frontend

A107663 a(2n) = 2*4^n-1, a(2n+1) = (2^(n+1)+1)^2; interlaces A083420 with A028400.

1, 9, 7, 25, 31, 81, 127, 289, 511, 1089, 2047, 4225, 8191, 16641, 32767, 66049, 131071, 263169, 524287, 1050625, 2097151, 4198401, 8388607, 16785409, 33554431, 67125249, 134217727, 268468225, 536870911, 1073807361, 2147483647

Offset: 0

Creighton Dement, May 19 2005

a(2n) = A085903(2n) = A083420(n).

Floretion Algebra Multiplication Program, FAMP Code: 4tesseq[A*B] with A = + .25'i + .25'j + .25'k + .25i' + .25j' + .25k' + .25'ii' + .25'jj' + .25'kk' + .25'ij' + .25'ik' + .25'ji' + .25'jk' + .25'ki' + .25'kj' + .25e and B = + .5'i + .5i' + 'ii' + e [Factor added to formula by Creighton Dement, Dec 11 2009]

Colin Barker, Table of n, a(n) for n = 0..1000
Henry Bottomley, Illustration of initial terms (A028400)
I. Strazdins, Universal affine classification of Boolean functions, Acta Applic. Math. 46 (1997), 147-167.
Index entries for linear recurrences with constant coefficients, signature (1,4,-2,-4).

Cf. A083420, A028400, A062510, A085903.

Vec((1 + 8*x - 6*x^2 - 16*x^3) / ((1 + x)*(1 - 2*x)*(1 - 2*x^2)) + O(x^35)) \\ Colin Barker, May 21 2019

G.f.: (-1-8*x+6*x^2+16*x^3) / ((1-2*x)*(x+1)*(2*x^2-1)).
From Colin Barker, May 21 2019: (Start)
a(n) = a(n-1) + 4*a(n-2) - 2*a(n-3) - 4*a(n-4) for n>3.
a(n) = ((-1)^(1+n) + 2^(1+n) + 2^((1+n)/2)*(1+(-1)^(1+n))).
(End)

A152977 Square array A(n,k), n>=0, k>=0, read by antidiagonals: A(n,k) is the number of partitions of 2^n into powers of 2 less than or equal to 2^k.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 2, 3, 1, 1, 2, 4, 5, 1, 1, 2, 4, 9, 9, 1, 1, 2, 4, 10, 25, 17, 1, 1, 2, 4, 10, 35, 81, 33, 1, 1, 2, 4, 10, 36, 165, 289, 65, 1, 1, 2, 4, 10, 36, 201, 969, 1089, 129, 1, 1, 2, 4, 10, 36, 202, 1625, 6545, 4225, 257, 1, 1, 2, 4, 10, 36, 202, 1827, 17361, 47905, 16641, 513, 1

Offset: 0

Alois P. Heinz, Jan 26 2011

Column sequences converge towards A002577.

			A(3,2) = 9, because there are 9 partitions of 2^3=8 into powers of 2 less than or equal to 2^2=4: [4,4], [4,2,2], [4,2,1,1], [4,1,1,1,1], [2,2,2,2], [2,2,2,1,1], [2,2,1,1,1,1], [2,1,1,1,1,1,1], [1,1,1,1,1,1,1,1].
Square array A(n,k) begins:
  1,  1,  1,   1,   1,   1,  ...
  1,  2,  2,   2,   2,   2,  ...
  1,  3,  4,   4,   4,   4,  ...
  1,  5,  9,  10,  10,  10,  ...
  1,  9, 25,  35,  36,  36,  ...
  1, 17, 81, 165, 201, 202,  ...

Alois P. Heinz, Antidiagonals n = 0..140, flattened

Columns k=0-10 give: A000012, A094373, A028400(n-2) for n>1, A210772, A210773, A210774, A210775, A210776, A210777, A210778, A210779.
Cf. A002577, A000123, A181322, A145515.
Main diagonal and lower diagonals give: A002577, A125792, A125794.

b:= proc(n,j) local nn, r;
      if n<0 then 0
    elif j=0 then 1
    elif j=1 then n+1
    elif n `if`(n=0, 1, b(2^(n-k), k)):
seq(seq(A(n, d-n), n=0..d), d=0..11);

b[n_, j_] := Module[{nn, r}, Which[n < 0, 0, j == 0, 1, j == 1, n+1, n < j, b[n, j] = b[n-1, j]+b[2*n, j-1], True, nn = 1+Floor[n]; r := n-nn; (nn-j)*Binomial[nn, j]*Sum[Binomial[j, h]/(nn-j+h)*b[j-h+r, j]*(-1)^h, {h, 0, j-1}]]]; a[n_, k_] := If[n == 0, 1, b[2^(n-k), k]]; Table[Table[a[n, d-n], {n, 0, d}], {d, 0, 11}] // Flatten (* Jean-François Alcover, Dec 18 2013, translated from Maple *)

A(n,k) = [x^2^(n-1)] 1/(1-x) * 1/Product_{j=0..k-1} (1-x^(2^j)) for n>0; A(0,k) = 1.

A092431 Numbers having in binary representation a leading 1 followed by n zeros and n-1 ones.

Original entry on oeis.org

2, 9, 35, 135, 527, 2079, 8255, 32895, 131327, 524799, 2098175, 8390655, 33558527, 134225919, 536887295, 2147516415, 8590000127, 34359869439, 137439215615, 549756338175, 2199024304127, 8796095119359, 35184376283135, 140737496743935, 562949970198527

Offset: 1

Reinhard Zumkeller, Mar 23 2004

Smallest numbers having in binary representation n 0's and n 1's: a(n) = Min{m: A023416(m)=A000120(m)=n}.

Vincenzo Librandi, Table of n, a(n) for n = 1..500
Eric Weisstein's World of Mathematics, Binary
Index entries for linear recurrences with constant coefficients, signature (7,-14,8).

Cf. A007088, A001700.
Subsequence of A031443.
Cf. A000120, A023416.
Cf. A007582, A056326, A005367, A063376, A032125, A056309, A028403, A001576, A028400, A049775.

LinearRecurrence[{7, -14, 8}, {2, 9, 35}, 40] (* Vladimir Joseph Stephan Orlovsky, Feb 20 2012 *)
Table[FromDigits[Join[PadRight[{1},n,0],PadRight[{},n-2,1]],2],{n,2,30}]//Sort (* or *) Rest[CoefficientList[Series[x (-2+5x)/((x-1)(2x-1)(4x-1)),{x,0,30}],x]] (* Harvey P. Dale, Jul 30 2021 *)

a(n+1) = 2*a(n) + 4^n + 1.
a(n) = 2^(2*n-1) + 2^(n-1) - 1.
a(n) = A007582(n)-1 = A056326(2n+1) = A005367(n-1)/2 = A063376(n)/2-1 = A032125(n+1)/3-1 = A056309(2n+1)/2 = A028403(n+1)/4-1 = (A001576(n)-3)/2 = (A028400(n+1)-9)/8 = Sum_{k=2..n+1} A049775(k). - Ralf Stephan, Mar 24 2004
G.f.: x*(-2+5*x) / ( (x-1)*(2*x-1)*(4*x-1) ). - R. J. Mathar, Jun 01 2011
E.g.f.: exp(x)*(exp(3*x) + exp(x) - 2)/2. - Stefano Spezia, Sep 27 2023

A060919 Number of corners in a 4-sided fractal.

Original entry on oeis.org

4, 8, 20, 60, 204, 748, 2860, 11180, 44204, 175788, 701100, 2800300, 11193004, 44755628, 178989740, 715893420, 2863442604, 11453508268, 45813508780, 183252986540, 733009849004, 2932035201708, 11728132418220, 46912512895660, 187650018028204, 750600005003948, 3002399885798060

Offset: 1

Henry Bottomley, Apr 10 2001

Harry J. Smith, Table of n, a(n) for n=1,...,200
Henry Bottomley, Illustration of initial terms
Index entries for linear recurrences with constant coefficients, signature (7,-14,8).

Cf. A007581, A002450, A028400.

LinearRecurrence[{7,-14,8},{4,8,20},30] (* Harvey P. Dale, Sep 01 2023 *)

a(n) = { (2^n + 2)*(2^n + 4)/6 } \\ Harry J. Smith, Jul 14 2009

a(n) = 4^n/6+2^n+4/3 = (2^n+2)*(2^n+4)/6 = 4*A007581(n-1) = 4(a(n-1)-1)-2^n = A028400(n-1)-A002450(n-1).
From Colin Barker, Nov 28 2012: (Start)
a(n) = 7*a(n-1)-14*a(n-2)+8*a(n-3).
G.f.: -4*x*(5*x^2-5*x+1) / ((x-1)*(2*x-1)*(4*x-1)). (End)
E.g.f.: (exp(4*x) + 6*exp(2*x) + 8*exp(x) - 15)/6. - Stefano Spezia, Dec 26 2024

A085903 Expansion of (1 + 2x^2)/((1 + x)(1 - 2x)(1 - 2*x^2)).

Original entry on oeis.org

1, 1, 7, 9, 31, 49, 127, 225, 511, 961, 2047, 3969, 8191, 16129, 32767, 65025, 131071, 261121, 524287, 1046529, 2097151, 4190209, 8388607, 16769025, 33554431, 67092481, 134217727, 268402689, 536870911, 1073676289, 2147483647

Offset: 1

Yuval Dekel (dekelyuval(AT)hotmail.com), Aug 16 2003

Resultant of the polynomial x^n - 1 and the Chebyshev polynomial of the first kind T_2(x).

This sequence is the case P1 = 1, P2 = 0, Q = -2 of the 3 parameter family of 4th-order linear divisibility sequences found by Williams and Guy. - Peter Bala, Apr 27 2014

Vincenzo Librandi, Table of n, a(n) for n = 1..1000
H. C. Williams and R. K. Guy, Some fourth-order linear divisibility sequences, Intl. J. Number Theory 7 (5) (2011) 1255-1277.
H. C. Williams and R. K. Guy, Some Monoapparitic Fourth Order Linear Divisibility Sequences Integers, Volume 12A (2012) The John Selfridge Memorial Volume
Index entries for linear recurrences with constant coefficients, signature (1,4,-2,-4).

Cf. A083420, A028400, A062510, A088037, A107663.

Cf. A060867. A100047.

[Round((Sqrt(2)^n - 1)*(Sqrt(2)^n - (-1)^n)): n in [1..40]]; // Vincenzo Librandi, Apr 28 2014

seq(simplify((sqrt(2)^n - 1)*(sqrt(2)^n - (-1)^n)), n = 1..30); # Peter Bala, Apr 27 2014

CoefficientList[ Series[(1 + 2x^2)/(1 - x - 4x^2 + 2x^3 + 4x^4), {x, 0, 30}], x] (* Robert G. Wilson v, May 04 2013 *)
LinearRecurrence[{1,4,-2,-4},{1,1,7,9},40] (* Harvey P. Dale, Jul 25 2016 *)

a(n) = polresultant(x^n - 1, 2*x^2 - 1) \\ David Wasserman, Feb 10 2005

def A085903(n): return (1<>1))-1)**2 # Chai Wah Wu, Jun 19 2024

a(2*n) = 2*4^n - 1, a(2*n + 1) = (2^n - 1)^2; interlaces A083420 with A060867 (squares of Mersenne numbers A000225). - Creighton Dement, May 19 2005
A107663(2*n) = a(2*n) = A083420(n). - Creighton Dement, May 19 2005
From Peter Bala, Apr 27 2014: (Start)
a(n) = (sqrt(2)^n - 1)*(sqrt(2)^n - (-1)^n).
a(n) = Product_{k = 1..n} ( 2 - exp(4*k*Pi*i/n) ). (End)
E.g.f.: exp(-x) + exp(2*x) - 2*cosh(sqrt(2)*x). - Ilya Gutkovskiy, Jun 16 2016

More terms from David Wasserman, Feb 10 2005

Edited by N. J. A. Sloane at the suggestion of Andrew S. Plewe, Jun 15 2007

A264871 Array read by antidiagonals: T(n,m) = (1+2^n)^m; n,m>=0.

Original entry on oeis.org

1, 2, 1, 4, 3, 1, 8, 9, 5, 1, 16, 27, 25, 9, 1, 32, 81, 125, 81, 17, 1, 64, 243, 625, 729, 289, 33, 1, 128, 729, 3125, 6561, 4913, 1089, 65, 1, 256, 2187, 15625, 59049, 83521, 35937, 4225, 129, 1, 512, 6561, 78125, 531441, 1419857, 1185921, 274625, 16641, 257

Offset: 0

R. J. Mathar, Nov 27 2015

			       1,       2,       4,       8,      16,      32,
       1,       3,       9,      27,      81,     243,
       1,       5,      25,     125,     625,    3125,
       1,       9,      81,     729,    6561,   59049,
       1,      17,     289,    4913,   83521, 1419857,
       1,      33,    1089,   35937, 1185921,39135393,

Cf. A000079 (row 0), A000244 (row 1), A000351 (row 2), A001019 (row 3), A001026 (row 4), A009977 (row 5), A000051 (column 1), A028400 (column 2), A136516 (main diagonal), A165327 (upper subdiagonal).

Reverse /@ Table[(1 + 2^(n - m))^m, {n, 0, 9}, {m, 0, n}] // Flatten (* Michael De Vlieger, Nov 27 2015 *)

G.f. for row n: 1/(1-(1+2^n)*x). - R. J. Mathar, Dec 15 2015

A213669 Irregular triangle read by rows: T(n,k) is the number of dominating subsets with k vertices of the double star graph G(n) obtained by joining with an edge the centers of two star trees each having n+1 vertices (n>=1, k>=2).

Original entry on oeis.org

4, 4, 1, 1, 6, 11, 6, 1, 1, 6, 17, 26, 22, 8, 1, 1, 8, 28, 58, 78, 68, 37, 10, 1, 1, 10, 45, 120, 212, 262, 230, 140, 56, 12, 1, 1, 12, 66, 220, 495, 794, 936, 822, 535, 250, 79, 14, 1, 1, 14, 91, 364, 1001, 2002, 3005, 3446, 3045, 2072, 1071, 406, 106, 16, 1

Offset: 1

Emeric Deutsch, Jul 10 2012

Number of entries in row n is 2n+1.
Sum of entries in row n is (2^n +1)^2 = A028400(n).
The Matula-Goebel number of the rooted tree obtained from G(n), by selecting the center of one of the trees as the root, is 2^n*(2^n-th prime); (knowing this, see A212630 for another approach to find this sequence).
Closely related to the connected domination polynomial of the n-book graph (divided by x^2), which is 1 less in the 3rd-to-last term of each row. - Eric W. Weisstein, May 12 2017

			Row 1 is 4,4,1 because the graph G(1) is the path abcd; there are 4 dominating subsets of size 2 (ac,ad,bc,bd), 4 dominating subsets of size 3 (abc,abd,acd,bcd) and 1 dominating subset of size 4 (abcd).
Triangle starts:
  4,  4,  1;
  1,  6, 11,  6,  1;
  1,  6, 17, 26, 22,  8,  1;
  1,  8, 28, 58, 78, 68, 37, 10,  1;

S. Alikhani and Y. H. Peng, Introduction to domination polynomial of a graph, arXiv:0905.2251 [math.CO], 2009.
S. Akbari, S. Alikhani, and Y. H. Peng, Characterization of graphs using domination polynomials, European J. Comb., 31, 2010, 1714-1724.
T. Kotek, J. Preen, F. Simon, P. Tittmann, and M. Trinks, Recurrence relations and splitting formulas for the domination polynomial, arXiv:1206.5926 [math.CO], 2012.
Eric Weisstein's World of Mathematics, Book Graph
Eric Weisstein's World of Mathematics, Connected Dominating Set

Cf. A028400, A212630.

P := proc (n) options operator, arrow: (x^n+x*(1+x)^n)^2 end proc: for n to 9 do seq(coeff(P(n), x, k), k = 2 .. 2*n+2) end do; # yields sequence in triangular form

T[n_, k_] := SeriesCoefficient[(x^n + x (1 + x)^n)^2, {x, 0, k}];
Table[T[n, k], {n, 1, 9}, {k, 2, 2 n + 2}] // Flatten (* Jean-François Alcover, Dec 06 2017 *)

The generating polynomial of row n is (x^n + x(1+x)^n)^2; this is the domination polynomial of the graph G(n).

The domination polynomial of the double star graph obtained by joining with an edge the center of a star tree having m+1 vertices and the center of a star tree having n+1 vertices is (x^m+x(1+x)^m)*(x^n + x(1+x)^n) (m,n >=1).

cp's OEIS Frontend

A107663 a(2n) = 2*4^n-1, a(2n+1) = (2^(n+1)+1)^2; interlaces A083420 with A028400.

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A152977 Square array A(n,k), n>=0, k>=0, read by antidiagonals: A(n,k) is the number of partitions of 2^n into powers of 2 less than or equal to 2^k.

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A092431 Numbers having in binary representation a leading 1 followed by n zeros and n-1 ones.

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A060919 Number of corners in a 4-sided fractal.

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A085903 Expansion of (1 + 2*x^2)/((1 + x)*(1 - 2*x)*(1 - 2*x^2)).

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A264871 Array read by antidiagonals: T(n,m) = (1+2^n)^m; n,m>=0.

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A213669 Irregular triangle read by rows: T(n,k) is the number of dominating subsets with k vertices of the double star graph G(n) obtained by joining with an edge the centers of two star trees each having n+1 vertices (n>=1, k>=2).

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A085903 Expansion of (1 + 2x^2)/((1 + x)(1 - 2x)(1 - 2*x^2)).