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 1-7 of 7 results.

A111006 Another version of Fibonacci-Pascal triangle A037027.

Original entry on oeis.org

1, 0, 1, 0, 1, 2, 0, 0, 2, 3, 0, 0, 1, 5, 5, 0, 0, 0, 3, 10, 8, 0, 0, 0, 1, 9, 20, 13, 0, 0, 0, 0, 4, 22, 38, 21, 0, 0, 0, 0, 1, 14, 51, 71, 34, 0, 0, 0, 0, 0, 5, 40, 111, 130, 55, 0, 0, 0, 0, 0, 1, 20, 105, 233, 235, 89, 0, 0, 0, 0, 0, 0, 6, 65, 256, 474, 420, 144
Offset: 0

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Author

Philippe Deléham, Oct 02 2005

Keywords

Comments

Triangle T(n,k), 0 <= k <= n, read by rows, given by [0, 1, -1, 0, 0, 0, 0, 0, 0, 0, ...] DELTA [1, 1, -1, 0, 0, 0, 0, 0, 0, ...] where DELTA is the operator defined in A084938.
Row sums are the Jacobsthal numbers A001045(n+1) and column sums form Pell numbers A000129.
Maximal column entries: A038149 = {1, 1, 2, 5, 10, 22, ...}.
T(n,k) gives a convolved Fibonacci sequence (A001629, A001872, ...).
Triangle read by rows: T(n,n-k) is the number of ways to tile a 2 X n rectangle with k pieces of 2 X 2 tiles and n-2k pieces of 1 X 2 tiles (0 <= k <= floor(n/2)). - Philippe Deléham, Feb 17 2014
Diagonal sums are A013979(n). - Philippe Deléham, Feb 17 2014
T(n,k) is the number of ways to tile a 2 X n rectangle with k pieces of 2 X 2 tiles and 1 X 2 tiles. - Emeric Deutsch, Aug 14 2014

Examples

			Triangle begins:
  1;
  0, 1;
  0, 1, 2;
  0, 0, 2, 3;
  0, 0, 1, 5,  5;
  0, 0, 0, 3, 10,  8;
  0, 0, 0, 1,  9, 20, 13;
  0, 0, 0, 0,  4, 22, 38,  21;
  0, 0, 0, 0,  1, 14, 51,  71,  34;
  0, 0, 0, 0,  0,  5, 40, 111, 130,  55;
  0, 0, 0, 0,  0,  1, 20, 105, 233, 235,  89;
  0, 0, 0, 0,  0,  0,  6,  65, 256, 474, 420, 144;
		

Crossrefs

Cf. A000045, A000129, A001045, A037027, A038112, A038149, A084938, A128100 (reversed version).
Some other Fibonacci-Pascal triangles: A027926, A036355, A037027, A074829, A105809, A109906, A114197, A162741, A228074.

Programs

  • Haskell
    a111006 n k = a111006_tabl !! n !! k
    a111006_row n = a111006_tabl !! n
    a111006_tabl =  map fst $ iterate (\(us, vs) ->
       (vs, zipWith (+) (zipWith (+) ([0] ++ us ++ [0]) ([0,0] ++ us))
                        ([0] ++ vs))) ([1], [0,1])
    -- Reinhard Zumkeller, Aug 15 2013

Formula

T(0, 0) = 1, T(n, k) = 0 for k < 0 or for n < k, T(n, k) = T(n-1, k-1) + T(n-2, k-1) + T(n-2, k-2).
T(n, k) = A037027(k, n-k). T(n, n) = A000045(n+1). T(3n, 2n) = (n+1)*A001002(n+1) = A038112(n).
G.f.: 1/(1-yx(1-x)-x^2*y^2). - Paul Barry, Oct 04 2005
Sum_{k=0..n} x^k*T(n,k) = (-1)^n*A053524(n+1), (-1)^n*A083858(n+1), (-1)^n*A002605(n), A033999(n), A000007(n), A001045(n+1), A083099(n) for x = -4, -3, -2, -1, 0, 1, 2 respectively. - Philippe Deléham, Dec 02 2006
Sum_{k=0..n} T(n,k)*x^(n-k) = A053404(n), A015447(n), A015446(n), A015445(n), A015443(n), A015442(n), A015441(n), A015440(n), A006131(n), A006130(n), A001045(n+1), A000045(n+1) for x = 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0 respectively. - Philippe Deléham, Feb 17 2014

A015540 a(n) = 5*a(n-1) + 6*a(n-2), a(0) = 0, a(1) = 1.

Original entry on oeis.org

0, 1, 5, 31, 185, 1111, 6665, 39991, 239945, 1439671, 8638025, 51828151, 310968905, 1865813431, 11194880585, 67169283511, 403015701065, 2418094206391, 14508565238345, 87051391430071, 522308348580425, 3133850091482551, 18803100548895305, 112818603293371831
Offset: 0

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Author

Keywords

Comments

Number of walks of length n between any two distinct vertices of the complete graph K_7. Example: a(2)=5 because the walks of length 2 between the vertices A and B of the complete graph ABCDEFG are ACB, ADB, AEB, AFB and AGB. - Emeric Deutsch, Apr 01 2004
Pisano period lengths: 1, 1, 2, 2, 2, 2, 14, 2, 2, 2, 10, 2, 12, 14, 2, 2, 16, 2, 18, 2, ... - R. J. Mathar, Aug 10 2012
Sum_{i=0..m} (-1)^(m+i)*6^i, for m >= 0, gives all terms after 0. - Bruno Berselli, Aug 28 2013
The ratio a(n+1)/a(n) converges to 6 as n approaches infinity. Also A053524, A080424, A051958. - Felix P. Muga II, Mar 09 2014

Examples

			G.f. = x + 5*x^2 + 31*x^3 + 185*x^4 + 1111*x^5 + 6665*x^6 + 39991*x^7 + ...
		

Crossrefs

Partial sums are in A033116. Cf. A014987.

Programs

  • Magma
    [Floor(6^n/7-(-1)^n/7): n in [0..30]]; // Vincenzo Librandi, Jun 24 2011
    
  • Maple
    seq(round(6^n/7),n=0..25); # Mircea Merca, Dec 28 2010
  • Mathematica
    k=0; lst={k}; Do[k = 6^n-k; AppendTo[lst, k], {n, 0, 5!}];lst (* Vladimir Joseph Stephan Orlovsky, Dec 11 2008 *)
    CoefficientList[Series[x / ((1 - 6 x) (1 + x)), {x, 0, 50}], x] (* Vincenzo Librandi, Mar 26 2014 *)
    LinearRecurrence[{5,6},{0,1},30] (* Harvey P. Dale, May 12 2015 *)
  • PARI
    my(x='x+O('x^30)); concat([0], Vec(x/((1-6*x)*(1+x)))) \\ G. C. Greubel, Jan 24 2018
    
  • PARI
    a(n) = round(6^n/7); \\ Altug Alkan, Sep 05 2018
  • Sage
    [lucas_number1(n,5,-6) for n in range(21)] # Zerinvary Lajos, Apr 24 2009
    

Formula

a(n) = 5*a(n-1) + 6*a(n-2).
From Paul Barry, Apr 20 2003: (Start)
a(n) = (6^n - (-1)^n)/7.
G.f.: x/((1-6*x)*(1+x)).
E.g.f.: (exp(6*x) - exp(-x))/7. (End)
a(n) = 6^(n-1) - a(n-1). - Emeric Deutsch, Apr 01 2004
a(n+1) = Sum_{k=0..n} binomial(n-k, k)*5^(n-2*k)*6^k. - Paul Barry, Jul 29 2004
a(n) = round(6^n/7). - Mircea Merca, Dec 28 2010
a(n) = (-1)^(n-1)*Sum_{k=0..n-1} A135278(n-1,k)*(-7)^k = (6^n - (-1)^n)/7 = (-1)^(n-1)*Sum_{k=0..n-1} (-6)^k. Equals (-1)^(n-1)*Phi(n,-6), where Phi is the cyclotomic polynomial when n is an odd prime. (For n > 0.) - Tom Copeland, Apr 14 2014

A100851 Triangle read by rows: T(n,k) = 2^n * 3^k, 0 <= k <= n, n >= 0.

Original entry on oeis.org

1, 2, 6, 4, 12, 36, 8, 24, 72, 216, 16, 48, 144, 432, 1296, 32, 96, 288, 864, 2592, 7776, 64, 192, 576, 1728, 5184, 15552, 46656, 128, 384, 1152, 3456, 10368, 31104, 93312, 279936, 256, 768, 2304, 6912, 20736, 62208, 186624, 559872, 1679616, 512, 1536, 4608, 13824, 41472, 124416, 373248, 1119744, 3359232, 10077696
Offset: 0

Views

Author

Reinhard Zumkeller, Nov 20 2004

Keywords

Examples

			From _Stefano Spezia_, Apr 28 2024: (Start)
Triangle begins:
   1;
   2,  6;
   4, 12,  36;
   8, 24,  72, 216;
  16, 48, 144, 432, 1296;
  32, 96, 288, 864, 2592, 7776;
  ...
(End)
		

Crossrefs

Programs

Formula

T(n,0) = A000079(n).
T(n,1) = A007283(n) for n>0.
T(n,2) = A005010(n) for n>1.
T(n,n) = A000400(n) = A100852(n,n).
Sum_{k=0..n} T(n, k) = A016129(n).
T(2*n, n) = A001021(n). - Reinhard Zumkeller, Mar 04 2006
G.f.: 1/((1 - 2*x)*(1 - 6*x*y)). - Stefano Spezia, Apr 28 2024
From G. C. Greubel, Nov 11 2024: (Start)
Sum_{k=0..n} (-1)^k*T(n, k) = A053524(n+1).
Sum_{k=0..floor(n/2)} T(n-k, k) = (1/2)*((1-(-1)^n)*A248337((n+1)/2) + (1 + (-1)^n)*A016149(n/2)).
Sum_{k=0..floor(n/2)} (-1)^k*T(n-k, k) = (1/2)*(-1)^floor(n/2)*( (1+(-1)^n) *A051958((n+2)/2) + 2*(1-(-1)^n)*A051958((n+1)/2)). (End)
Sum_{n>=0, k=0..n} 1/T(n,k) = 12/5. - Amiram Eldar, May 12 2025

A083232 a(n) = (3*7^n+(-1)^n)/4.

Original entry on oeis.org

1, 5, 37, 257, 1801, 12605, 88237, 617657, 4323601, 30265205, 211856437, 1482995057, 10380965401, 72666757805, 508667304637, 3560671132457, 24924697927201, 174472885490405, 1221310198432837, 8549171389029857
Offset: 0

Views

Author

Paul Barry, Apr 23 2003

Keywords

Comments

Binomial transform of A053524 (without leading zero).

Crossrefs

Cf. A083233.

Programs

Formula

a(n) = (3*7^n+(-1)^n)/4.
G.f.: (1-x)/((1-7*x)*(1+x)).
E.g.f.: (3*exp(7*x)+exp(-x))/4

A053536 Expansion of 1/((1+4*x)*(1-12*x)).

Original entry on oeis.org

1, 8, 112, 1280, 15616, 186368, 2240512, 26869760, 322502656, 3869769728, 46438285312, 557255229440, 6687079530496, 80244887257088, 962938915520512, 11555265912504320, 138663195245019136, 1663958325760360448, 19967499977843802112, 239609999459247718400
Offset: 0

Views

Author

Barry E. Williams, Jan 15 2000

Keywords

References

  • A. H. Beiler, Recreations in the Theory of Numbers, Dover, N.Y., 1964, pp. 194-196.

Crossrefs

Cf. A015518.

Programs

  • GAP
    a:=[1,8];; for n in [3..30] do a[n]:=8*a[n-1]+48*a[n-2]; od; a; # G. C. Greubel, May 16 2019
  • Magma
    R:=PowerSeriesRing(Integers(), 30); Coefficients(R!( 1/((1+4*x)*(1-12*x)) )); // G. C. Greubel, May 16 2019
    
  • Mathematica
    LinearRecurrence[{8,48}, {1,8}, 30] (* G. C. Greubel, May 16 2019 *)
  • PARI
    Vec(1/((1+4*x)*(1-12*x)) + O(x^30)) \\ Michel Marcus, Dec 03 2014
    
  • Sage
    (1/((1+4*x)*(1-12*x))).series(x, 30).coefficients(x, sparse=False) # G. C. Greubel, May 16 2019
    

Formula

a(n) = (4^n/4)*(3^(n+1) + (-1)^n).
a(n) = 8*a(n-1) + 48*a(n-2), with a(0)=1, a(1)=8.
E.g.f.: (3*exp(12*x) + exp(-4*x))/4. - G. C. Greubel, May 16 2019
a(n) = 2^n*A053524(n+1). - R. J. Mathar, Mar 08 2021

Extensions

Terms a(12) onward added by G. C. Greubel, May 16 2019

A083231 a(n) = (3*5^n + (-3)^n)/4.

Original entry on oeis.org

1, 3, 21, 87, 489, 2283, 11901, 58047, 294609, 1459923, 7338981, 36576807, 183238329, 915128763, 4578832461, 22884596367, 114451679649, 572172304803, 2861119804341, 14304824180727, 71526445426569, 357625253564043
Offset: 0

Views

Author

Paul Barry, Apr 23 2003

Keywords

Crossrefs

Cf. A083232, A053524 (binomial transform, shifted).

Programs

Formula

a(n) = (3*5^n + (-3)^n)/4.
G.f.: (1+x)/((1-5*x)*(1+3*x)).
E.g.f.: (3*exp(5*x) + exp(-3*x))/4.

A099139 a(n) = (18^n - (-6)^n)/24.

Original entry on oeis.org

0, 1, 12, 252, 4320, 79056, 1415232, 25520832, 459095040, 8265390336, 148766948352, 2677865536512, 48201216860160, 867624080265216, 15617220384079872, 281110045277601792, 5059980344811847680, 91079649027723165696, 1639433665572357537792, 29509806081862392348672
Offset: 0

Views

Author

Paul Barry, Sep 29 2004

Keywords

Comments

In general k^(n-1)*A015518(n) is given by ((3k)^n-(-k)^n)/(4k) with g.f. x/((1+kx)(1-3kx)).

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{12,108},{0,1},20] (* Harvey P. Dale, May 24 2015 *)

Formula

G.f.: x/((1+6x)*(1-18x)).
a(n) = 12a(n-1)+108a(n-2). a(n) = 6^(n-1)*A015518(n).
Showing 1-7 of 7 results.