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 1-10 of 13 results. Next

A258993 Triangle read by rows: T(n,k) = binomial(n+k,n-k), k = 0..n-1.

Original entry on oeis.org

1, 1, 3, 1, 6, 5, 1, 10, 15, 7, 1, 15, 35, 28, 9, 1, 21, 70, 84, 45, 11, 1, 28, 126, 210, 165, 66, 13, 1, 36, 210, 462, 495, 286, 91, 15, 1, 45, 330, 924, 1287, 1001, 455, 120, 17, 1, 55, 495, 1716, 3003, 3003, 1820, 680, 153, 19, 1, 66, 715, 3003, 6435, 8008, 6188, 3060, 969, 190, 21
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 22 2015

Keywords

Comments

T(n,k) = A085478(n,k) = A007318(A094727(n),A004736(k)), k = 0..n-1;
rounded(T(n,k)/(2*k+1)) = A258708(n,k);
rounded(sum(T(n,k)/(2*k+1)): k = 0..n-1) = A000967(n).

Examples

			.  n\k |  0  1    2    3     4     5     6     7    8    9  10 11
. -----+-----------------------------------------------------------
.   1  |  1
.   2  |  1  3
.   3  |  1  6    5
.   4  |  1 10   15    7
.   5  |  1 15   35   28     9
.   6  |  1 21   70   84    45    11
.   7  |  1 28  126  210   165    66    13
.   8  |  1 36  210  462   495   286    91    15
.   9  |  1 45  330  924  1287  1001   455   120   17
.  10  |  1 55  495 1716  3003  3003  1820   680  153   19
.  11  |  1 66  715 3003  6435  8008  6188  3060  969  190  21
.  12  |  1 78 1001 5005 12870 19448 18564 11628 4845 1330 231 23  .
		

Crossrefs

If a diagonal of 1's is added on the right, this becomes A085478.
Essentially the same as A143858.
Cf. A027941 (row sums), A117671 (central terms), A143858, A000967, A258708.
T(n,k): A000217 (k=1), A000332 (k=2), A000579 (k=3), A000581 (k=4), A001287 (k=5), A010965 (k=6), A010967 (k=7), A010969 (k=8), A010971 (k=9), A010973 (k=10), A010975 (k=11), A010977 (k=12), A010979 (k=13), A010981 (k=14), A010983 (k=15), A010985 (k=16), A010987 (k=17), A010989 (k=18), A010991 (k=19), A010993 (k=20), A010995 (k=21), A010997 (k=22), A010999 (k=23), A011001 (k=24), A017714 (k=25), A017716 (k=26), A017718 (k=27), A017720 (k=28), A017722 (k=29), A017724 (k=30), A017726 (k=31), A017728 (k=32), A017730 (k=33), A017732 (k=34), A017734 (k=35), A017736 (k=36), A017738 (k=37), A017740 (k=38), A017742 (k=39), A017744 (k=40), A017746 (k=41), A017748 (k=42), A017750 (k=43), A017752 (k=44), A017754 (k=45), A017756 (k=46), A017758 (k=47), A017760 (k=48), A017762 (k=49), A017764 (k=50).
T(n+k,n): A005408 (k=1), A000384 (k=2), A000447 (k=3), A053134 (k=4), A002299 (k=5), A053135 (k=6), A053136 (k=7), A053137 (k=8), A053138 (k=9), A196789 (k=10).
Cf. A165253.

Programs

  • GAP
    Flat(List([1..12], n-> List([0..n-1], k-> Binomial(n+k,n-k) ))); # G. C. Greubel, Aug 01 2019
  • Haskell
    a258993 n k = a258993_tabl !! (n-1) !! k
    a258993_row n = a258993_tabl !! (n-1)
    a258993_tabl = zipWith (zipWith a007318) a094727_tabl a004736_tabl
    
  • Magma
    [Binomial(n+k,n-k): k in [0..n-1], n in [1..12]]; // G. C. Greubel, Aug 01 2019
    
  • Mathematica
    Table[Binomial[n+k,n-k], {n,1,12}, {k,0,n-1}]//Flatten (* G. C. Greubel, Aug 01 2019 *)
  • PARI
    T(n,k) = binomial(n+k,n-k);
    for(n=1, 12, for(k=0,n-1, print1(T(n,k), ", "))) \\ G. C. Greubel, Aug 01 2019
    
  • Sage
    [[binomial(n+k,n-k) for k in (0..n-1)] for n in (1..12)] # G. C. Greubel, Aug 01 2019
    

Formula

T(n,k) = A085478(n,k) = A007318(A094727(n),A004736(k)), k = 0..n-1;
rounded(T(n,k)/(2*k+1)) = A258708(n,k);
rounded(sum(T(n,k)/(2*k+1)): k = 0..n-1) = A000967(n).

A121314 Triangle T(n,k), 0 <= k <= n, read by rows given by [0, 1, 0, 0, 0, 0, ...] DELTA [1, 0, 1, 0, 0, 0, 0, 0, 0, 0, ...] where DELTA is the operator defined in A084938.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 1, 3, 1, 0, 1, 5, 6, 1, 0, 1, 7, 15, 10, 1, 0, 1, 9, 28, 35, 15, 1, 0, 1, 11, 45, 84, 70, 21, 1, 0, 1, 13, 66, 165, 210, 126, 28, 1, 0, 1, 15, 91, 286, 495, 462, 210, 36, 1
Offset: 0

Views

Author

Philippe Deléham, Aug 25 2006

Keywords

Comments

A054142 with first diagonal 1, 0, 0, 0, 0, 0, 0, 0, ...
Mirror image of triangle in A165253.

Examples

			Triangle begins
  1;
  0,  1;
  0,  1,  1;
  0,  1,  3,  1;
  0,  1,  5,  6,  1;
  0,  1,  7, 15, 10,  1;
  0,  1,  9, 28, 35, 15,  1;
  0,  1, 11, 45, 84, 70, 21,  1;
		

Crossrefs

Formula

T(0,0)=1; T(n,0)=0 for n > 0; T(n+1,k+1) = binomial(2*n-k,k)for n >= 0 and k >= 0.
Sum_{k=0..n} T(n,k)*x^k = A001519(n), A047849(n), A165310(n), A165311(n), A165312(n), A165314(n), A165322(n), A165323(n), A165324(n) for x = 1,2,3,4,5,6,7,8,9 respectively.
Sum_{k=0..n} 2^k*T(n,k) = (4^n+2)/3.
Sum_{k=0..n} 2^(n-k)*T(n,k) = A001835(n).
Sum_{k=0..n} 3^k*4^(n-k)*T(n,k) = A054879(n). - Philippe Deléham, Aug 26 2006
Sum_{k=0..n} T(n,k)*(-1)^k*2^(3n-2k) = A143126(n). - Philippe Deléham, Oct 31 2008
Sum_{k=0..n} T(n,k)*(-1)^k*3^(n-k) = A138340(n)/4^n. - Philippe Deléham, Nov 01 2008
G.f.: (1-(y+1)*x)/(1-(2y+1)*x+y^2*x^2). - Philippe Deléham, Nov 01 2011
T(n,k) = T(n-1,k) + 2*T(n-1,k-1) - T(n-2,k-2), T(0,0) = T(1,1) = 1, T(1,0) = 0. - Philippe Deléham, Feb 19 2012

A165310 a(0)=1, a(1)=3, a(n) = 7*a(n-1) - 9*a(n-2) for n > 1.

Original entry on oeis.org

1, 3, 12, 57, 291, 1524, 8049, 42627, 225948, 1197993, 6352419, 33684996, 178623201, 947197443, 5022773292, 26634636057, 141237492771, 748950724884, 3971517639249, 21060066950787, 111676809902268, 592197066758793
Offset: 0

Views

Author

Philippe Deléham, Sep 14 2009

Keywords

Comments

a(n)/a(n-1) tends to (7+sqrt(13))/2 = 5.30277563... = 2+A098316.
For n >= 2, a(n) equals 3^n times the permanent of the (2n-2) X (2n-2) matrix with 1/sqrt(3)'s along the main diagonal, and 1's along the superdiagonal and the subdiagonal. - John M. Campbell, Jul 08 2011

Crossrefs

Programs

  • Magma
    I:=[1,3]; [n le 2 select I[n] else 7*Self(n-1)-9*Self(n-2): n in [1..30]]; // Vincenzo Librandi, Sep 24 2011
  • Mathematica
    LinearRecurrence[{7,-9},{1,3},30] (* Harvey P. Dale, Sep 23 2011 *)

Formula

G.f.: (1-4x)/(1-7x+9x^2).
a(n) = Sum_{k=0..n} A165253(n,k)*3^(n-k).
a(n) = ((13-sqrt(13))*(7+sqrt(13))^n+(13+sqrt(13))*(7-sqrt(13))^n )/(26*2^n). - Klaus Brockhaus, Sep 26 2009

A123970 Triangle read by rows: T(0,0)=1; T(n,k) is the coefficient of x^(n-k) in the monic characteristic polynomial of the n X n matrix (min(i,j)) (i,j=1,2,...,n) (0 <= k <= n, n >= 1).

Original entry on oeis.org

1, 1, -1, 1, -3, 1, 1, -6, 5, -1, 1, -10, 15, -7, 1, 1, -15, 35, -28, 9, -1, 1, -21, 70, -84, 45, -11, 1, 1, -28, 126, -210, 165, -66, 13, -1, 1, -36, 210, -462, 495, -286, 91, -15, 1, 1, -45, 330, -924, 1287, -1001, 455, -120, 17, -1, 1, -55, 495, -1716, 3003, -3003, 1820, -680, 153, -19, 1, 1, -66, 715, -3003, 6435, -8008
Offset: 0

Views

Author

Gary W. Adamson and Roger L. Bagula, Oct 29 2006

Keywords

Comments

This sequence is the same as A129818 up to sign. - T. D. Noe, Sep 30 2011
Riordan array (1/(1-x), -x/(1-x)^2). - Philippe Deléham, Feb 18 2012

Examples

			Triangular sequence (gives the odd Tutte-Beraha constants as roots!) begins:
  1;
  1,  -1;
  1,  -3,   1;
  1,  -6,   5,   -1;
  1, -10,  15,   -7,    1;
  1, -15,  35,  -28,    9,    -1;
  1, -21,  70,  -84,   45,   -11,   1;
  1, -28, 126, -210,  165,   -66,  13,   -1;
  1, -36, 210, -462,  495,  -286,  91,  -15,  1;
  1, -45, 330, -924, 1287, -1001, 455, -120, 17, -1;
  ...
		

References

  • S. Beraha, Infinite non-trivial families of maps and chromials, Ph.D. thesis. Baltimore, MD: Johns Hopkins University, 1975.
  • Steven R. Finch, Mathematical Constants (Encyclopedia of Mathematics and its Applications), chapter 5.25.
  • W. T. Tutte, "More about Chromatic Polynomials and the Golden Ratio." In Combinatorial Structures and their Applications: Proc. Calgary Internat. Conf., Calgary, Alberta, 1969. New York: Gordon and Breach, p. 439, 1969.

Crossrefs

Cf. A109954, A129818, A143858, A165253. - R. J. Mathar, Jan 10 2011
Modulo signs, inverse matrix to A039599.

Programs

  • Magma
    /* As triangle */ [[(-1)^k*Binomial(n + k, 2*k): k in [0..n]]: n in [0.. 15]]; // Vincenzo Librandi, Jan 04 2019
  • Maple
    with(linalg): m:=(i,j)->min(i,j): M:=n->matrix(n,n,m): T:=(n,k)->coeff(charpoly(M(n),x),x,n-k): 1; for n from 1 to 11 do seq(T(n,k),k=0..n) od; # yields sequence in triangular form
  • Mathematica
    An[d_] := MatrixPower[Table[Min[n, m], {n, 1, d}, {m, 1, d}], -1]; Join[{{1}}, Table[CoefficientList[CharacteristicPolynomial[An[d], x], x], {d, 1, 20}]]; Flatten[%]

Formula

f(n,x) = (2x-1)f(n-1,x)-x^2*f(n-2,x), where f(n,x) is the characteristic polynomial of the n X n matrix from the definition and f(0,x)=1. See formula in Fendley and Krushkal. - Jonathan Vos Post, Nov 04 2007
T(n,k) = (-1)^k * A085478(n,k) = (-1)^n * A129818(n,k). - Philippe Deléham, Feb 06 2012
T(n,k) = 2*T(n-1,k) - T(n-1,k-1) - T(n-2,k), T(0,0)=T(1,0)=1, T(1,1)=-1, T(n,k)=0 if k < 0 or if k > n. - Philippe Deléham, Nov 29 2013

Extensions

Edited by N. J. A. Sloane, Nov 29 2006

A165312 a(0)=1, a(1)=5, a(n)=11*a(n-1)-25*a(n-2) for n>1.

Original entry on oeis.org

1, 5, 30, 205, 1505, 11430, 88105, 683405, 5314830, 41378005, 322287305, 2510710230, 19560629905, 152399173205, 1187375157630, 9251147403805, 72078242501105, 561581982417030, 4375445744059705, 34090353624231005
Offset: 0

Views

Author

Philippe Deléham, Sep 14 2009

Keywords

Comments

a(n)/a(n-1) tends to (11+sqrt(21))/2 = 7.79128784...
For n>=2, a(n) equals 5^n times the permanent of the (2n-2)X(2n-2) tridiagonal matrix with 1/sqrt(5)'s along the main diagonal, and 1's along the superdiagonal and the subdiagonal. [John M. Campbell, Jul 08 2011]

Crossrefs

Cf. A165253.

Programs

  • Mathematica
    LinearRecurrence[{11,-25},{1,5},30] (* Harvey P. Dale, Oct 02 2016 *)

Formula

G.f.: (1-6x)/(1-11x+25x^2).
a(n) = Sum_{k=0..n} A165253(n,k)*5^(n-k).
a(n) = ((21-sqrt(21))*(11+sqrt(21))^n+(21+sqrt(21))*(11-sqrt(21))^n )/(42*2^n). [Klaus Brockhaus, Sep 26 2009]

A165311 a(0)=1, a(1)=4, a(n)=9*a(n-1)-16*a(n-2) for n>1.

Original entry on oeis.org

1, 4, 20, 116, 724, 4660, 30356, 198644, 1302100, 8540596, 56031764, 367636340, 2412218836, 15827788084, 103854591380, 681446713076, 4471346955604, 29338975191220, 192509225431316, 1263159425822324, 8288287225499860
Offset: 0

Views

Author

Philippe Deléham, Sep 14 2009

Keywords

Comments

a(n)/a(n-1) tends to (9+sqrt(17))/2 = 6.56155281...

Programs

  • Mathematica
    LinearRecurrence[{9,-16},{1,4},30] (* Harvey P. Dale, Feb 19 2015 *)

Formula

G.f.: (1-5x)/(1-9x+16x^2). a(n)=Sum_{k, 0<=k<=n}A165253(n,k)*4^(n-k).
a(n) = ((17-sqrt(17))*(9+sqrt(17))^n+(17+sqrt(17))*(9-sqrt(17))^n )/(34*2^n). [From Klaus Brockhaus, Sep 26 2009]

A165314 a(0)=1, a(1)=6, a(n)=13*a(n-1)-36*a(n-2) for n>1.

Original entry on oeis.org

1, 6, 42, 330, 2778, 24234, 215034, 1923018, 17258010, 155125482, 1395342906, 12554940426, 112981880922, 1016786596650, 9150878043258, 82357097082954, 741210652521114, 6670882987788138, 60037895350485690, 540340851995941002
Offset: 0

Views

Author

Philippe Deléham, Sep 14 2009

Keywords

Comments

a(n)/a(n-1) tends to 9.

Formula

G.f.: (1-7x)/(1-13x+36x^2). a(n)=Sum_{k, 0<=k<=n}A165253(n,k)*6^(n-k).
a(n) = (2*9^n+3*4^n)/5. [From Klaus Brockhaus, Sep 26 2009]

A165322 a(0)=1, a(1)=7, a(n)=15*a(n-1)-49*a(n-2) for n>1.

Original entry on oeis.org

1, 7, 56, 497, 4711, 46312, 463841, 4688327, 47596696, 484222417, 4931098151, 50239573832, 511969798081, 5217807853447, 53180597695736, 542036380617137, 5524696422165991, 56310663682250152, 573949830547618721
Offset: 0

Views

Author

Philippe Deléham, Sep 14 2009

Keywords

Comments

a(n)/a(n-1) tends to (15+sqrt(29))/2=10,192582...
For n>=2, a(n) equals 7^n times the permanent of the (2n-2)X(2n-2) tridiagonal matrix with 1/sqrt(7)'s along the main diagonal, and 1's along the superdiagonal and the subdiagonal. [John M. Campbell, Jul 08 2011]

Crossrefs

Cf. A165253.

Programs

  • Mathematica
    LinearRecurrence[{15,-49},{1,7},20] (* Harvey P. Dale, Jun 04 2021 *)

Formula

G.f.: (1-8x)/(1-15x+49x^2).
a(n) = Sum_{k=0..n} A165253(n,k)*7^(n-k).
a(n) = ((29-sqrt(29))*(15+sqrt(29))^n+(29+sqrt(29))*(15-sqrt(29))^n )/(58*2^n). [Klaus Brockhaus, Sep 26 2009]

A165323 a(0)=1, a(1)=8, a(n)=17*a(n-1)-64*a(n-2) for n>1.

Original entry on oeis.org

1, 8, 72, 712, 7496, 81864, 911944, 10263752, 116119368, 1317149128, 14959895624, 170020681416, 1932918264136, 21978286879688, 249924108049992, 2842099476549832, 32320548186147656, 367554952665320904
Offset: 0

Views

Author

Philippe Deléham, Sep 14 2009

Keywords

Comments

a(n)/a(n-1) tends to (17+sqrt(33))/2 = 11.3722813...
For n>=2, a(n) equals 8^n times the permanent of the (2n-2) X (2n-2) tridiagonal matrix with 1/sqrt(8)'s along the main diagonal, and 1's along the superdiagonal and the subdiagonal. - John M. Campbell, Jul 08 2011

Crossrefs

Cf. A165253.

Programs

  • Mathematica
    LinearRecurrence[{17,-64},{1,8},20] (* Harvey P. Dale, Jun 08 2018 *)

Formula

G.f.: (1-9*x)/(1-17*x+64*x^2).
a(n) = Sum_{k=0..n} A165253(n,k)*8^(n-k).
a(n) = ((33-sqrt(33))*(17+sqrt(33))^n+(33+sqrt(33))*(17-sqrt(33))^n)/(66*2^n). - Klaus Brockhaus, Sep 28 2009

A165324 a(0)=1, a(1)=9, a(n)= 19*a(n-1)-81*a(n-2) for n>1.

Original entry on oeis.org

1, 9, 90, 981, 11349, 136170, 1667961, 20661489, 257463450, 3218224941, 40291734429, 504866733930, 6328837455921, 79353706214169, 995084584139610, 12478956895304901, 156498329695484709, 1962672755694512490
Offset: 0

Views

Author

Philippe Deléham, Sep 14 2009

Keywords

Comments

a(n)/a(n-1) tends to (19+sqrt(37))/2 = 12.5413812...

Programs

  • Mathematica
    LinearRecurrence[{19,-81},{1,9},20] (* Harvey P. Dale, Nov 20 2020 *)

Formula

G.f.: (1-10x)/(1-19x+81x^2). a(n)= Sum_{k, 0<=k<=n}A165253(n,k)*9^(n-k).
a(n) = ((37-sqrt(37))*(19+sqrt(37))^n+(37+sqrt(37))*(19-sqrt(37))^n)/(74*2^n). [From Klaus Brockhaus, Sep 28 2009]
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