A006100 -id:A006100 - cp's OEIS frontend

A024023 a(n) = 3^n - 1.

0, 2, 8, 26, 80, 242, 728, 2186, 6560, 19682, 59048, 177146, 531440, 1594322, 4782968, 14348906, 43046720, 129140162, 387420488, 1162261466, 3486784400, 10460353202, 31381059608, 94143178826, 282429536480, 847288609442, 2541865828328, 7625597484986, 22876792454960

Offset: 0

N. J. A. Sloane

Number of different directions along lines and hyper-diagonals in an n-dimensional cubic lattice for the attacking queens problem (A036464 in n=2, A068940 in n=3 and A068941 in n=4). The n-dimensional direction vectors have the a(n)+1 Cartesian coordinates (i,j,k,l,...) where i,j,k,l,... = -1, 0, or +1, excluding the zero-vector i=j=k=l=...=0. The corresponding hyper-line count is A003462. - R. J. Mathar, May 01 2006
Total number of sequences of length m=1,...,n with nonzero integer elements satisfying the condition Sum_{k=1..m} |n_k| <= n. See the K. A. Meissner link p. 6 (with a typo: it should be 3^([2a]-1)-1). - Wolfdieter Lang, Jan 21 2008
Let P(A) be the power set of an n-element set A and R be a relation on P(A) such that for all x, y of P(A), xRy if x and y are disjoint and either 0) x is a proper subset of y or y is a proper subset of x, or 1) x is not a subset of y and y is not a subset of x. Then a(n) = |R|. - Ross La Haye, Mar 19 2009
Number of neighbors in Moore's neighborhood in n dimensions. - Dmitry Zaitsev, Nov 30 2015
Number of terms in conjunctive normal form of Boolean expression with n variables. E.g., a(2) = 8: [~x, ~y, x, y, ~x|~y, ~x|y, x|~y, x|y]. - Yuchun Ji, May 12 2023
Number of rays of the Coxeter arrangement of type B_n. Equivalently, number of facets of the n-dimensional type B permutahedron. - Jose Bastidas, Sep 12 2023

			From _Zerinvary Lajos_, Jan 14 2007: (Start)
Ternary......decimal:
0...............0
2...............2
22..............8
222............26
2222...........80
22222.........242
222222........728
2222222......2186
22222222.....6560
222222222...19682
2222222222..59048
etc...........etc.
(End)
Sequence combinatorics: n=3: With length m=1: [1],[2],[3] each with 2 signs, with m=2: [1,1], [1,2], [2,1], each 2^2 = 4 times from choosing signs; m=3: [1,1,1] coming in 2^3 signed versions: 3*2 + 3*4 + 1*8 = 26 = a(3). The order is important, hence the M_0 multinomials A048996 enter as factors.
A027902 gives the 384 divisors of a(24). - _Reinhard Zumkeller_, Mar 11 2010

Mordechai Ben-Ari, Mathematical Logic for Computer Science, Third edition, 173-203.

Vincenzo Librandi, Table of n, a(n) for n = 0..200
Omran Ahmadi and Robert Granger, An efficient deterministic test for Kloosterman sum zeros, Mathematics of Computation, Vol. 83, No. 285 (2014), pp. 347-363; arXiv preprint, arXiv:1104.3882 [math.NT], 2011-2012. See 1st column of Table 2, p. 9.
Feryal Alayont and Evan Henning, Edge Covers of Caterpillars, Cycles with Pendants, and Spider Graphs, J. Int. Seq. (2023) Vol. 26, Art. 23.9.4.
Michael Baake, Franz Gähler, and Uwe Grimm, Examples of Substitution Systems and Their Factors, Journal of Integer Sequences, Vol. 16 (2013), #13.2.14.
R. Samuel Buss, Herbrand's Theorem, University of California, Logic and Computational Complexity pp. 195-209, Lecture Notes in Computer Science, vol 960. Springer.
Jan Draisma, Tyrrell B. McAllister and Benjamin Nill, Lattice width directions and Minkowski's 3^d-theorem, SIAM J. Discrete Math., Vol. 26, No. 3 (2012), pp. 1104-1107; arXiv preprint, arXiv:0901.1375 [math.CO], Jan 10 2009.
Alessandro Farinelli, Herbrand Universe and Herbrand Base.
Ross La Haye, Binary Relations on the Power Set of an n-Element Set, Journal of Integer Sequences, Vol. 12 (2009), Article 09.2.6.
Krzysztof A. Meissner, Black hole entropy in Loop Quantum Gravity, Classical and Quantum Gravity, Vol. 21, No. 22 (2004), pp. 5245--5251; arXiv preprint, arXiv:gr-qc/0407052, 2004.
Amir Sapir, The Tower of Hanoi with Forbidden Moves, The Computer J. 47 (1) (2004) 20, case three-in-a row, sequence b(n).
Steven Schlicker, Roman Vasquez, and Rachel Wofford, Integer Sequences from Configurations in the Hausdorff Metric Geometry via Edge Covers of Bipartite Graphs, J. Int. Seq. (2023) Vol. 26, Art. 23.6.6.
Amelia Carolina Sparavigna, The groupoids of Mersenne, Fermat, Cullen, Woodall and other Numbers and their representations by means of integer sequences, Politecnico di Torino, Italy (2019), [math.NT].
Amelia Carolina Sparavigna, Some Groupoids and their Representations by Means of Integer Sequences, International Journal of Sciences (2019) Vol. 8, No. 10.
Wikipedia, Herbrand Structure.
Damiano Zanardini, Computational Logic, Slides, UPM European Master in Computational Logic (EMCL) School of Computer Science Technical University of Madrid, 2009-2010.
Index entries for linear recurrences with constant coefficients, signature (4,-3).

Cf. triangle A013609.
Cf. A003462, A007051, A034472, A214369.
Cf. second column of A145901.

a024023 = subtract 1 . a000244  -- Reinhard Zumkeller, Jun 30 2013

[3^n-1: n in [0..35]]; // Vincenzo Librandi, Apr 30 2011

3^Range[0,30]-1 (* Paolo Xausa, Jul 15 2023 *)

a(n)=3^n-1 \\ Charles R Greathouse IV, Sep 24 2015

vector(50, n, sum(k=0, n, 2^k*binomial(n-1, k))-1) \\ Altug Alkan, Oct 04 2015

my(x='x+O('x^100)); concat([0], Vec(2*x/(-1+x)/(-1+3*x))) \\ Altug Alkan, Oct 16 2015

a(n) = A000244(n) - 1.
a(n) = 2*A003462(n). - R. J. Mathar, May 01 2006
A128760(a(n)) > 0. - Reinhard Zumkeller, Mar 25 2007
G.f.: 2*x/((-1+x)*(-1+3*x)) = 1/(-1+x) - 1/(-1+3*x). - R. J. Mathar, Nov 19 2007
a(n) = Sum_{k=1..n} Sum_{m=1..k} binomial(k-1,m-1)*2^m, n >= 1. a(0)=0. From the sequence combinatorics mentioned above. Twice partial sums of powers of 3.
E.g.f.: e^(3*x) - e^x. - Mohammad K. Azarian, Jan 14 2009
a(n) = A024101(n)/A034472(n). - Reinhard Zumkeller, Feb 14 2009
a(n) = 3*a(n-1) + 2 (with a(0)=0). - Vincenzo Librandi, Nov 19 2010
E.g.f.: -E(0) where E(k) = 1 - 3^k/(1 - x/(x - 3^k*(k+1)/E(k+1) )); (continued fraction). - Sergei N. Gladkovskii, Dec 06 2012
a(n) = A227048(n,A020914(n)). - Reinhard Zumkeller, Jun 30 2013
Sum_{n>=1} 1/a(n) = A214369. - Amiram Eldar, Nov 11 2020
a(n) = Sum_{k=1..n} 2^k*binomial(n,k). - Ridouane Oudra, Jun 15 2025
From Peter Bala, Jul 01 2025: (Start)
For n >= 1, a(2*n)/a(n) = A034472(n) and a(3*n)/a(n) = A034513(n).
Modulo differences in offsets, exp( Sum_{n >= 1} a(k*n)/a(n)*x^n/n ) is the o.g.f. of A003462 (k = 2), A006100 (k = 3), A006101 (k = 4), A006102 (k = 5), A022196 (k = 6), A022197 (k = 7), A022198 (k = 8), A022199 (k = 9), A022200 (k = 10), A022201 (k = 11), A022202 (k = 12) and A022203 (k = 13).
The following are all examples of telescoping series:
Sum_{n >= 1} 3^n/(a(n)*a(n+1)) = 1/2^2; Sum_{n >= 1} 3^n/(a(n)*a(n+1)*a(n+2)) = 1/(2*8^2).
In general, for k >= 1, Sum_{n >= 1} 3^n/(a(n)*a(n+1)*...*a(n+k)) = 1/(a(1)*a(2)*...*a(k)*a(k)).
Sum_{n >= 1} 3^n/(a(n)*a(n+2)) = 5/64; Sum_{n >= 1} (-3)^n/(a(n)*a(n+2)) = -3/64.
Sum_{n >= 1} 3^n/(a(n)*a(n+4)) = 703/83200; Sum_{n >= 1} (-3)^n/(a(n)*a(n+4)) = - 417/83200. (End)

A022167 Triangle of Gaussian binomial coefficients [ n,k ] for q = 3.

Original entry on oeis.org

1, 1, 1, 1, 4, 1, 1, 13, 13, 1, 1, 40, 130, 40, 1, 1, 121, 1210, 1210, 121, 1, 1, 364, 11011, 33880, 11011, 364, 1, 1, 1093, 99463, 925771, 925771, 99463, 1093, 1, 1, 3280, 896260, 25095280, 75913222, 25095280, 896260, 3280, 1

Offset: 0

N. J. A. Sloane

The coefficients of the matrix inverse are apparently given by T^(-1)(n,k) = (-1)^n*A157783(n,k). - R. J. Mathar, Mar 12 2013

			Triangle begins:
  1;
  1,    1;
  1,    4,      1;
  1,   13,     13,        1;
  1,   40,    130,       40,        1;
  1,  121,   1210,     1210,      121,        1;
  1,  364,  11011,    33880,    11011,      364,      1;
  1, 1093,  99463,   925771,   925771,    99463,   1093,    1;
  1, 3280, 896260, 25095280, 75913222, 25095280, 896260, 3280, 1;

F. J. MacWilliams and N. J. A. Sloane, The Theory of Error-Correcting Codes, Elsevier-North Holland, 1978, p. 698.
M. Sved, Gaussians and binomials, Ars. Combinatoria, 17A (1984), 325-351.

T. D. Noe, Rows n = 0..50 of triangle, flattened
R. Mestrovic, Lucas' theorem: its generalizations, extensions and applications (1878--2014), arXiv preprint arXiv:1409.3820 [math.NT], 2014.
Kent E. Morrison, Integer Sequences and Matrices Over Finite Fields, Journal of Integer Sequences, Vol. 9 (2006), Article 06.2.1.
M. Sved, Gaussians and binomials, Ars. Combinatoria, 17A (1984), 325-351. (Annotated scanned copy)
Index entries for sequences related to Gaussian binomial coefficients

Columns k=0..3 give A000012, A003462, A006100, A006101.

Cf. A006117 (row sums).

A022167 := proc(n,m)
        A027871(n)/A027871(n-m)/A027871(m) ;
end proc:
seq(seq(A022167(n,m),m=0..n),n=0..10) ; # R. J. Mathar, Nov 14 2011

p[n_] := Product[3^k-1, {k, 1, n}]; t[n_, m_] := p[n]/(p[n-m]*p[m]); Table[t[n, m], {n, 0, 10}, {m, 0, n}] // Flatten (* Jean-François Alcover, Jan 10 2014, after R. J. Mathar *)
Table[QBinomial[n, k, 3], {n, 0, 10}, {k, 0, n}] // Flatten
(* or, after Vladimir Kruchinin, using S for qStirling2: *)
S[n_, k_, q_] /; 1 <= k <= n := S[n-1, k-1, q] + Sum[q^j, {j, 0, k-1}]* S[n-1, k, q]; S[n_, 0, ] := KroneckerDelta[n, 0]; S[0, k, ] := KroneckerDelta[0, k]; S[, , ] = 0;
T[n_, k_] /; n >= k := Sum[Binomial[n, j]*S[n-j, n-k, q]*(q-1)^(k-j) /. q -> 3, {j, 0, k}];
Table[T[n, k], {n, 0, 10}, {k, 0, n}] // Flatten (* Jean-François Alcover, Mar 08 2020 *)

T(n,k) = T(n-1,k-1) + q^k * T(n-1,k). - Peter A. Lawrence, Jul 13 2017
T(n,k) = Sum_{j=0..k} C(n,j)*qStirling2(n-j,n-k,3)*(2)^(k-j),j,0,k), n >= k, where qStirling2(n,k,3) is triangle A333143. - Vladimir Kruchinin, Mar 07 2020
G.f. of column k: x^k * exp( Sum_{j>=1} f((k+1)*j)/f(j) * x^j/j ), where f(j) = 3^j - 1. - Seiichi Manyama, May 09 2025

A016142 Expansion of 1/((1-3x)(1-9*x)).

Original entry on oeis.org

1, 12, 117, 1080, 9801, 88452, 796797, 7173360, 64566801, 581120892, 5230147077, 47071500840, 423644039001, 3812797945332, 34315186290957, 308836690967520, 2779530261754401, 25015772484929772, 225141952751788437, 2026277575928357400, 18236498186842001001, 164128483692038362212

Offset: 0

N. J. A. Sloane

a(n) is the number of lattices L in Z^(n+1) such that the quotient group Z^(n+1) / L is C_9. - Álvar Ibeas, Nov 29 2015

In the game of SET with four attributes there are 1080 potential SETs. See A090245. In the generalized game of SET with different numbers of attributes, the number of potential SETs is a(n+1). - Robert Price, Oct 14 2017

Vincenzo Librandi, Table of n, a(n) for n = 0..200
A. M. Hinz, S. Klavžar, U. Milutinović, C. Petr, The Tower of Hanoi - Myths and Maths, Birkhäuser 2013. See page 100. Book's website.
Index entries for linear recurrences with constant coefficients, signature (12,-27).

Cf. A006100, A090245.

[(1/6)*(9^(n+1)-3^(n+1)): n in [0..20]]; // Vincenzo Librandi, Feb 24 2014

Join[{a=1,b=12},Table[c=12*b-27*a;a=b;b=c,{n,60}]] (* Vladimir Joseph Stephan Orlovsky, Jan 31 2011 *)
CoefficientList[Series[1/((1-3x)(1-9x)),{x,0,20}],x] (* or *) Table[ (9^(n+1) -3^(n+1))/6,{n,0,20}]  (* Harvey P. Dale, Apr 03 2011 *)
Table[ncards = 3^nattr; (ncards*(ncards - 1))/6, {nattr, 1, 20}] (* Robert Price, Oct 14 2017 *)

Vec(1/((1-3*x)*(1-9*x))+O(x^99)) \\ Charles R Greathouse IV, Sep 26 2012

a(n) = (1/6)*(9^(n+1) - 3^(n+1)); \\ Joerg Arndt, Feb 23 2014

[lucas_number1(n,12,27) for n in range(1, 20)] # Zerinvary Lajos, Apr 27 2009

a(n) = (1/6)*(9^(n+1) - 3^(n+1)).
a(n-1) = Sum_{i=1..n} binomial(n,i)*3^(n-i)*6^(i-1). - Sam Handler (sam_5_5_5_0(AT)yahoo.com), Jun 29 2004
a(n) = 12*a(n-1) - 27*a(n-2), a(0)=1, a(1)=12. - Vincenzo Librandi, Mar 14 2011
a(n) = A006100(n+2) - A006100(n+1), for n > 0. - Álvar Ibeas, Nov 29 2015
E.g.f.: exp(3*x)*(3*exp(3*x) - 1)/2. - Elmo R. Oliveira, Mar 08 2025

A203243 Second elementary symmetric function of the first n terms of (1,3,9,27,81,...).

Original entry on oeis.org

3, 39, 390, 3630, 33033, 298389, 2688780, 24208860, 217909263, 1961271939, 17651713170, 158866215690, 1429798332693, 12868192168689, 115813751041560, 1042323823944120, 9380914609207323, 84428232063996639, 759854090319361950

Offset: 2

Clark Kimberling, Dec 31 2011

Index entries for linear recurrences with constant coefficients, signature (13,-39,27).

Cf. A006100.

f[k_] := 3^(k - 1); t[n_] := Table[f[k], {k, 1, n}]
a[n_] := SymmetricPolynomial[2, t[n]]
Table[a[n], {n, 2, 32}]    (* A203243 *)
Table[a[n]/3, {n, 2, 32}]  (* A006100 *)

Vec(-3*x^2/((x-1)*(3*x-1)*(9*x-1)) + O(x^100)) \\ Colin Barker, Aug 15 2014

a(n) = 3*A006100(n).
From Colin Barker, Aug 15 2014: (Start)
a(n) = (3-4*3^n+9^n)/16.
a(n) = 13*a(n-1)-39*a(n-2)+27*a(n-3).
G.f.: -3*x^2 / ((x-1)*(3*x-1)*(9*x-1)). (End)

A128119 Square array T(n,m) read by antidiagonals: number of sublattices of index m in generic n-dimensional lattice.

Original entry on oeis.org

1, 1, 1, 1, 3, 1, 1, 7, 4, 1, 1, 15, 13, 7, 1, 1, 31, 40, 35, 6, 1, 1, 63, 121, 155, 31, 12, 1, 1, 127, 364, 651, 156, 91, 8, 1, 1, 255, 1093, 2667, 781, 600, 57, 15, 1, 1, 511, 3280, 10795, 3906, 3751, 400, 155, 13, 1, 1, 1023, 9841, 43435, 19531, 22932, 2801, 1395, 130, 18, 1

Offset: 1

Ralf Stephan, May 09 2007

Differs from sum of divisors of m^(n-1) in 4th column!

			Array starts:
1,1,1,1,1,1,1,1,1,
1,3,4,7,6,12,8,15,13,
1,7,13,35,31,91,57,155,130,
1,15,40,155,156,600,400,1395,1210,
1,31,121,651,781,3751,2801,11811,11011,
1,63,364,2667,3906,22932,19608,97155,99463,
1,127,1093,10795,19531,138811,137257,788035,896260,
1,255,3280,43435,97656,836400,960800,6347715,8069620,

Günter Scheja, Uwe Storch, Lehrbuch der Algebra, Teil 2. BG Teubner, Stuttgart, 1988. [§63, Aufg. 13]

Álvar Ibeas, First 100 antidiagonals, flattened
Michael Baake, Solution of the coincidence problem in dimensions d≤4, arXiv:math/0605222 [math.MG], 2006. [Appx. A]
B. Gruber, Alternative formulas for the number of sublattices, Acta Cryst. A53 (1997) 807-808.
Yi Ming Zou, Gaussian binomials and the number of sublattices, arXiv:math/0610684 [math.CO], 2006.

Rows include A000203, A001001, A038991, A038992, A038993, A038994, A038995, A038996, A038997, A038998, A038999.
Columns include A000225, A003462, A006095, A003463, A160869, A023000, A006096, A006100, A046915.
Transposed array is A160870.

T[n_, m_] := If[m == 1, 1, Product[{p, e} = pe; (p^(e+j)-1)/(p^j-1), {pe, FactorInteger[m]}, {j, 1, n-1}]];
Table[T[n-m+1, m], {n, 1, 11}, {m, 1, n}] // Flatten (* Jean-François Alcover, Dec 10 2018 *)

T(n,m)=local(k,v);v=factor(m);k=matsize(v)[1];prod(i=1,k,prod(j=1,n-1,(v[i,1]^(v[i,2]+j)-1)/(v[i,1]^j-1)))

Dirichlet g.f. of n-th row: Product_{i=0..n-1} zeta(s-i).
If m is squarefree, T(n,m) = A000203(m^(n-1)). - Álvar Ibeas, Jan 17 2015
T(n, Product(p^e)) = Product(Gaussian_poly[e+n-1, e]p). - _Álvar Ibeas, Oct 31 2015

Edited by Charles R Greathouse IV, Oct 28 2009

A021694 Expansion of 1/((1-x)(1-3x)(1-9x)(1-11x)).

Original entry on oeis.org

1, 24, 394, 5544, 71995, 891408, 10701748, 125788848, 1456313749, 16673208552, 189289198462, 2135136588312, 23963101915663, 267883518461856, 2985323286760936, 33185997429018336, 368172943255604137

Offset: 0

N. J. A. Sloane

Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (24,-182,456,-297).

Cf. A006100, A018091 (first differences).

m:=20; R:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/((1-x)*(1-3*x)*(1-9*x)*(1-11*x)))); // Bruno Berselli, May 07 2013

CoefficientList[Series[1/((1 - x) (1 - 3 x) (1 - 9 x) (1 - 11 x)), {x, 0, 20}], x] (* Bruno Berselli, May 07 2013 *)
LinearRecurrence[{24,-182,456,-297},{1,24,394,5544},20] (* Harvey P. Dale, Mar 01 2022 *)

Vec(1/((1-x)*(1-3*x)*(1-9*x)*(1-11*x))+O(x^20)) \\ Bruno Berselli, May 07 2013

G.f.: 1/((1-x)*(1-3*x)*(1-9*x)*(1-11*x)).
a(n) = -1/160 +3^(n+2)/32 -3^(2n+5)/32 +11^(n+3)/160. [Bruno Berselli, May 07 2013]
a(n)-11*a(n-1) = A006100(n+2). [Bruno Berselli, May 08 2013]

A099583 a(n) = Sum_{k=0..floor(n/2)} binomial(n-k, k-1)2^(n-k-1)(3/2)^(k-1).

Original entry on oeis.org

0, 0, 1, 2, 10, 26, 91, 260, 820, 2420, 7381, 22022, 66430, 198926, 597871, 1792520, 5380840, 16139240, 48427561, 145272842, 435848050, 1307514626, 3922632451, 11767808780, 35303692060, 105910810460, 317733228541, 953198888462

Offset: 0

Paul Barry, Oct 23 2004

In general, a(n) = Sum_{k=0..floor(n/2)} binomial(n-k, k-1)*u^(n-k-1)*(v/u)^(k-1) has g.f. x^2/((1-v*x^2)(1-u*x-v*x^2)) and satisfies the recurrence a(n) = u*a(n-1) + 2v*a(n-2) - u*v*a(n-3) - v^2*a(n-4).

G. C. Greubel, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (2,6,-6,-9).

Cf. A006100, A002452.

I:=[0,0,1,2]; [n le 4 select I[n] else 2*Self(n-1) +6*Self(n-2) -6*Self(n-3) -9*Self(n-4): n in [1..41]]; // G. C. Greubel, Jul 22 2022

LinearRecurrence[{2,6,-6,-9}, {0,0,1,2}, 40] (* G. C. Greubel, Jul 22 2022 *)

a(n) = sum(k=0, n\2, binomial(n-k, k-1)*2^(n-k-1)*(3/2)^(k-1)); \\ Michel Marcus, Jan 20 2018

[(1/8)*(3^n -(-1)^n -2*(1-(-1)^n)*3^((n-1)/2)) for n in (0..40)] # G. C. Greubel, Jul 22 2022

G.f.: x^2/((1-3*x^2)*(1-2*x-3*x^2)).
a(n) = 2*a(n-1) + 6*a(n-2) - 6*a(n-3) - 9*a(n-4).
a(n) = A002452(n/2) if n even; a(n) = 2*A006100((n+1)/2) if n odd. - R. J. Mathar, Jun 06 2010
a(0)=0, a(1)=0; a(2)=1; a(n) = 2*a(n-1) + 3*a(n-2) if n is odd; a(n) = 2*a(n-1) + 3*a(n-2) + 3^m (m=1,2,3...) if n is even. - Vincenzo Librandi, Jun 26 2010
From G. C. Greubel, Jul 22 2022: (Start)
a(n) = (1/8)*(3^n - (-1)^n - 2*(1-(-1)^n)*3^((n-1)/2) ).
E.g.f.: (1/12)*(3*exp(x)*sinh(2*x) - 2*sqrt(3)*sinh(sqrt(3)*x)). (End)

A109774 a(n) = (3^(n-1) - 1) * (3^n - 1)/2.

Original entry on oeis.org

0, 8, 104, 1040, 9680, 88088, 795704, 7170080, 64556960, 581091368, 5230058504, 47071235120, 423643241840, 3812795553848, 34315179116504, 308836669444160, 2779530197184320, 25015772291219528, 225141952170657704, 2026277574184965200, 18236498181611824400

Offset: 1

R. K. Guy, Aug 14 2005

Index entries for linear recurrences with constant coefficients, signature (13,-39,27).

Cf. A006100.

A109774:=n->(3^(n-1) - 1) * (3^n - 1)/2: seq(A109774(n), n=1..30); # Wesley Ivan Hurt, Jan 24 2017

From R. J. Mathar, Nov 07 2015: (Start)
G.f.: -8*x^2/((x - 1)*(3*x - 1)*(9*x - 1)).
a(n) = 8*A006100(n). (End)
E.g.f.: exp(x)*(3 - 4*exp(2*x) + exp(8*x))/6. - Stefano Spezia, Apr 03 2023

a(21) from Stefano Spezia, Apr 03 2023

A177730 Expansion of (6x + 1) / ((x - 1)(2x - 1)(4x - 1)(8*x - 1)).

Original entry on oeis.org

1, 21, 245, 2325, 20181, 168021, 1370965, 11075925, 89042261, 714081621, 5719635285, 45785027925, 366392038741, 2931583636821, 23454458533205, 187642826282325, 1501171242849621, 12009484474209621, 96076333921424725, 768612503886583125, 6148907361161794901

Offset: 0

Roger L. Bagula, May 12 2010

Muniru A Asiru, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (15,-70,120,-64).

Cf. A006095, A006100.

a := List([0..200],n->((2^(n+1)-1)^2*(2^(n+2)-1))/3); # Muniru A Asiru, Jan 27 2018

a := seq(((2^(n+1)-1)^2 * (2^(n+2)-1))/3, n = 0..200); # Muniru A Asiru, Jan 27 2018

CoefficientList[Series[(6x+1)/((x-1)(2x-1)(4x-1)(8x-1)),{x,0,30}],x] (* or *) LinearRecurrence[{15,-70,120,-64},{1,21,245,2325},30] (* Harvey P. Dale, Jul 16 2018 *)

Vec((6*x + 1) / ((x - 1)*(2*x - 1)*(4*x - 1)*(8*x - 1)) + O(x^30)) \\ Colin Barker, Jan 27 2018

From Colin Barker, Jan 27 2018: (Start)
a(n) = ((2^(n+1)-1)^2 * (2^(n+2)-1)) / 3.
a(n) = 15*a(n-1) - 70*a(n-2) + 120*a(n-3) - 64*a(n-4) for n>3.
(End)

Heavily edited, with the blessing of Michel Marcus and Joerg Arndt, by Colin Barker, Jan 27 2018

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