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 1-8 of 8 results.

A164881 Inverse of A164844.

Original entry on oeis.org

1, 10, 1, 100, 9, 1, 1000, 91, 8, 1, 10000, 909, 83, 7, 1, 100000, 9091, 826, 76, 6, 1, 1000000, 90909, 8265, 750, 70, 5, 1, 10000000, 909091, 82644, 7515, 680, 65, 4, 1
Offset: 1

Views

Author

Mark Dols, Aug 29 2009

Keywords

Examples

			1
10,1
100,9,1
1000,91,8,1
10000,909,83,7,1
100000,9091,826,76,6,1
1000000,90909,8265,750,70,5,1
10000000,909091,82644,7515,680,65,4,1
		

Crossrefs

A168647 Reverse (palindrome) of A164844.

Original entry on oeis.org

1, 1, 1, 1, 11, 1, 1, 21, 111, 1, 1, 31, 321, 1111, 1, 1, 41, 631, 4321, 11111, 1, 1, 51, 51, 731, 54321, 111111, 1, 1, 61, 561, 251, 51731, 654321, 1111111, 1, 1, 71, 181, 5861, 53251, 171731, 7654321, 11111111, 1, 1, 81, 891, 6681, 2961, 604251, 8371731, 87654321, 111111111, 1
Offset: 0

Views

Author

Mark Dols, Dec 01 2009

Keywords

Examples

			1
1,1
1,11,1
1,21,111,1
1,31,321,1111,1
1,41,631,4321,11111,1
		

Crossrefs

Formula

T(n,k) = A004086(A164844(n,k)).

Extensions

a(24) onward corrected by Georg Fischer, Apr 08 2022

A180175 Diagonal sums of A164844.

Original entry on oeis.org

1, 10, 101, 1011, 10112, 101123, 1011235, 10112358, 101123593, 1011235951, 10112359544, 101123595495, 1011235955039, 10112359550534, 101123595505573, 1011235955056107, 10112359550561680, 101123595505617787, 1011235955056179467, 10112359550561797254
Offset: 1

Views

Author

Mark Dols, Aug 15 2010

Keywords

Comments

Sums are built along inclined lines through the triangle with (1,2)-steps in the (row,column) indices. - R. J. Mathar, Aug 19 2010

Examples

			From _R. J. Mathar_, Aug 19 2010: (Start)
One example is a(5), the sum of numbers in parentheses:
  1;
  1, 10;
  (1), 11, 100;
  1, 12, (111) ; 1000;;
  1, 13, 123 ; 1111, (10000); (End)
		

Crossrefs

Formula

From R. J. Mathar, Aug 19 2010: (Start)
G.f.: ( 1-x ) / ( (10*x-1)*(x^2+x-1) ).
a(n) = +11*a(n-1) -9*a(n-2) -10*a(n-3).
a(n) = (90*10^n -A022100(n))/89. (End)

Extensions

More terms from R. J. Mathar, Aug 19 2010

A228196 A triangle formed like Pascal's triangle, but with n^2 on the left border and 2^n on the right border instead of 1.

Original entry on oeis.org

0, 1, 2, 4, 3, 4, 9, 7, 7, 8, 16, 16, 14, 15, 16, 25, 32, 30, 29, 31, 32, 36, 57, 62, 59, 60, 63, 64, 49, 93, 119, 121, 119, 123, 127, 128, 64, 142, 212, 240, 240, 242, 250, 255, 256, 81, 206, 354, 452, 480, 482, 492, 505, 511, 512, 100, 287, 560, 806, 932, 962, 974, 997, 1016, 1023, 1024
Offset: 1

Views

Author

Boris Putievskiy, Aug 15 2013

Keywords

Comments

The third row is (n^4 - n^2 + 24*n + 24)/12.
For a closed-form formula for generalized Pascal's triangle see A228576. - Boris Putievskiy, Sep 04 2013

Examples

			The start of the sequence as a triangular array read by rows:
   0;
   1,  2;
   4,  3,  4;
   9,  7,  7,  8;
  16, 16, 14, 15, 16;
  25, 32, 30, 29, 31, 32;
  36, 57, 62, 59, 60, 63, 64;
		

Crossrefs

Cf. We denote Pascal-like triangle with L(n) on the left border and R(n) on the right border by (L(n),R(n)). A007318 (1,1), A008949 (1,2^n), A029600 (2,3), A029618 (3,2), A029635 (1,2), A029653 (2,1), A037027 (Fibonacci(n),1), A051601 (n,n) n>=0, A051597 (n,n) n>0, A051666 (n^2,n^2), A071919 (1,0), A074829 (Fibonacci(n), Fibonacci(n)), A074909 (1,n), A093560 (3,1), A093561 (4,1), A093562 (5,1), A093563 (6,1), A093564 (7,1), A093565 (8,1), A093644 (9,1), A093645 (10,1), A095660 (1,3), A095666 (1,4), A096940 (1,5), A096956 (1,6), A106516 (3^n,1), A108561(1,(-1)^n), A132200 (4,4), A134636 (2n+1,2n+1), A137688 (2^n,2^n), A160760 (3^(n-1),1), A164844(1,10^n), A164847 (100^n,1), A164855 (101*100^n,1), A164866 (101^n,1), A172171 (1,9), A172185 (9,11), A172283 (-9,11), A177954 (int(n/2),1), A193820 (1,2^n), A214292 (n,-n), A227074 (4^n,4^n), A227075 (3^n,3^n), A227076 (5^n,5^n), A227550 (n!,n!), A228053 ((-1)^n,(-1)^n), A228074 (Fibonacci(n), n).
Cf. A000290 (row 1), A153056 (row 2), A000079 (column 1), A000225 (column 2), A132753 (column 3), A118885 (row sums of triangle array + 1), A228576 (generalized Pascal's triangle).

Programs

  • GAP
    T:= function(n,k)
        if k=0 then return n^2;
        elif k=n then return 2^n;
        else return T(n-1,k-1) + T(n-1,k);
        fi;
      end;
    Flat(List([0..12], n-> List([0..n], k-> T(n,k) ))); # G. C. Greubel, Nov 12 2019
  • Maple
    T:= proc(n, k) option remember;
          if k=0 then n^2
        elif k=n then 2^k
        else T(n-1, k-1) + T(n-1, k)
          fi
        end:
    seq(seq(T(n, k), k=0..n), n=0..10); # G. C. Greubel, Nov 12 2019
  • Mathematica
    T[n_, k_]:= T[n, k] = If[k==0, n^2, If[k==n, 2^k, T[n-1, k-1] + T[n-1, k]]]; Table[T[n, k], {n,0,10}, {k,0,n}]//Flatten (* G. C. Greubel, Nov 12 2019 *)
    Flatten[Table[Sum[i^2 Binomial[n-1-i, n-k-i], {i,1,n-k}] + Sum[2^i Binomial[n-1-i, k-i], {i,1,k}], {n,0,10}, {k,0,n}]] (* Greg Dresden, Aug 06 2022 *)
  • PARI
    T(n,k) = if(k==0, n^2, if(k==n, 2^k, T(n-1, k-1) + T(n-1, k) )); \\ G. C. Greubel, Nov 12 2019
    
  • Python
    def funcL(n):
       q = n**2
       return q
    def funcR(n):
       q = 2**n
       return q
    for n in range (1,9871):
       t=int((math.sqrt(8*n-7) - 1)/ 2)
       i=n-t*(t+1)/2-1
       j=(t*t+3*t+4)/2-n-1
       sum1=0
       sum2=0
       for m1 in range (1,i+1):
          sum1=sum1+funcR(m1)*binomial(i+j-m1-1,i-m1)
       for m2 in range (1,j+1):
          sum2=sum2+funcL(m2)*binomial(i+j-m2-1,j-m2)
       sum=sum1+sum2
    
  • Sage
    @CachedFunction
    def T(n, k):
        if (k==0): return n^2
        elif (k==n): return 2^n
        else: return T(n-1, k-1) + T(n-1, k)
    [[T(n, k) for k in (0..n)] for n in (0..12)] # G. C. Greubel, Nov 12 2019
    

Formula

T(n,0) = n^2, n>0; T(0,k) = 2^k; T(n, k) = T(n-1, k-1) + T(n-1, k) for n,k > 0. [corrected by G. C. Greubel, Nov 12 2019]
Closed-form formula for general case. Let L(m) and R(m) be the left border and the right border of Pascal like triangle, respectively. We denote binomial(n,k) by C(n,k).
As table read by antidiagonals T(n,k) = Sum_{m1=1..n} R(m1)*C(n+k-m1-1, n-m1) + Sum_{m2=1..k} L(m2)*C(n+k-m2-1, k-m2); n,k >=0.
As linear sequence a(n) = Sum_{m1=1..i} R(m1)*C(i+j-m1-1, i-m1) + Sum_{m2=1..j} L(m2)*C(i+j-m2-1, j-m2), where i=n-t*(t+1)/2-1, j=(t*t+3*t+4)/2-n-1, t=floor((-1+sqrt(8*n-7))/2); n>0.
Some special cases. If L(m)={b,b,b...} b*A000012, then the second sum takes form b*C(n+k-1,j). If L(m) is {0,b,2b,...} b*A001477, then the second sum takes form b*C(n+k,n-1). Similarly for R(m) and the first sum.
For this sequence L(m)=m^2 and R(m)=2^m.
As table read by antidiagonals T(n,k) = Sum_{m1=1..n} (2^m1)*C(n+k-m1-1, n-m1) + Sum_{m2=1..k} (m2^2)*C(n+k-m2-1, k-m2); n,k >=0.
As linear sequence a(n) = Sum_{m1=1..i} (2^m1)*C(i+j-m1-1, i-m1) + Sum_{m2=1..j} (m2^2)*C(i+j-m2-1, j-m2), where i=n-t*(t+1)/2-1, j=(t*t+3*t+4)/2-n-1, t=floor((-1+sqrt(8*n-7))/2).
As a triangular array read by rows, T(n,k) = Sum_{i=1..n-k} i^2*C(n-1-i, n-k-i) + Sum_{i=1..k} 2^i*C(n-1-i, k-i); n,k >=0. - Greg Dresden, Aug 06 2022

Extensions

Cross-references corrected and extended by Philippe Deléham, Dec 27 2013

A108561 Triangle read by rows: T(n,0)=1, T(n,n)=(-1)^n, T(n+1,k)=T(n,k-1)+T(n,k) for 0 < k < n.

Original entry on oeis.org

1, 1, -1, 1, 0, 1, 1, 1, 1, -1, 1, 2, 2, 0, 1, 1, 3, 4, 2, 1, -1, 1, 4, 7, 6, 3, 0, 1, 1, 5, 11, 13, 9, 3, 1, -1, 1, 6, 16, 24, 22, 12, 4, 0, 1, 1, 7, 22, 40, 46, 34, 16, 4, 1, -1, 1, 8, 29, 62, 86, 80, 50, 20, 5, 0, 1, 1, 9, 37, 91, 148, 166, 130, 70, 25, 5, 1, -1, 1, 10, 46, 128, 239, 314, 296, 200, 95, 30, 6, 0, 1, 1, 11, 56, 174, 367
Offset: 0

Views

Author

Reinhard Zumkeller, Jun 10 2005

Keywords

Comments

Sum_{k=0..n} T(n,k) = A078008(n);
Sum_{k=0..n} abs(T(n,k)) = A052953(n-1) for n > 0;
T(n,1) = n - 2 for n > 1;
T(n,2) = A000124(n-3) for n > 2;
T(n,3) = A003600(n-4) for n > 4;
T(n,n-6) = A001753(n-6) for n > 6;
T(n,n-5) = A001752(n-5) for n > 5;
T(n,n-4) = A002623(n-4) for n > 4;
T(n,n-3) = A002620(n-1) for n > 3;
T(n,n-2) = A008619(n-2) for n > 2;
T(n,n-1) = n mod 2 for n > 0;
T(2*n,n) = A072547(n+1).
Sum_{k=0..n} T(n,k)*x^k = A232015(n), A078008(n), A000012(n), A040000(n), A001045(n+2), A140725(n+1) for x = 2, 1, 0, -1, -2, -3 respectively. - Philippe Deléham, Nov 17 2013, Nov 19 2013
(1,a^n) Pascal triangle with a = -1. - Philippe Deléham, Dec 27 2013
T(n,k) = A112465(n,n-k). - Reinhard Zumkeller, Jan 03 2014

Examples

			From _Philippe Deléham_, Nov 17 2013: (Start)
Triangle begins:
  1;
  1, -1;
  1,  0,  1;
  1,  1,  1, -1;
  1,  2,  2,  0,  1;
  1,  3,  4,  2,  1, -1;
  1,  4,  7,  6,  3,  0,  1; (End)
		

Crossrefs

Cf. A007318 (a=1), A008949(a=2), A164844(a=10).
Similar to the triangles A035317, A059259, A080242, A112555.
Cf. A072547 (central terms).

Programs

  • GAP
    Flat(List([0..13],n->List([0..n],k->Sum([0..k],i->Binomial(n,i)*(-2)^(k-i))))); # Muniru A Asiru, Feb 19 2018
  • Haskell
    a108561 n k = a108561_tabl !! n !! k
    a108561_row n = a108561_tabl !! n
    a108561_tabl = map reverse a112465_tabl
    -- Reinhard Zumkeller, Jan 03 2014
    
  • Maple
    A108561 := (n, k) -> add(binomial(n, i)*(-2)^(k-i), i = 0..k):
    seq(seq(A108561(n,k), k = 0..n), n = 0..12); # Peter Bala, Feb 18 2018
  • Mathematica
    Clear[t]; t[n_, 0] = 1; t[n_, n_] := t[n, n] = (-1)^Mod[n, 2]; t[n_, k_] := t[n, k] = t[n-1, k] + t[n-1, k-1]; Table[t[n, k], {n, 0, 13}, {k, 0, n}] // Flatten (* Jean-François Alcover, Mar 06 2013 *)
  • Sage
    def A108561_row(n):
        @cached_function
        def prec(n, k):
            if k==n: return 1
            if k==0: return 0
            return -prec(n-1,k-1)-sum(prec(n,k+i-1) for i in (2..n-k+1))
        return [(-1)^k*prec(n, k) for k in (1..n-1)]+[(-1)^(n+1)]
    for n in (1..12): print(A108561_row(n)) # Peter Luschny, Mar 16 2016
    

Formula

G.f.: (1-y*x)/(1-x-(y+y^2)*x). - Philippe Deléham, Nov 17 2013
T(n,k) = T(n-1,k) + T(n-2,k-1) + T(n-2,k-2), 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 17 2013
From Peter Bala, Feb 18 2018: (Start)
T(n,k) = Sum_{i = 0..k} binomial(n,i)*(-2)^(k-i), 0 <= k <= n.
The n-th row polynomial is the n-th degree Taylor polynomial of the rational function (1 + x)^n/(1 + 2*x) about 0. For example, for n = 4, (1 + x)^4/(1 + 2*x) = 1 + 2*x + 2*x^2 + x^4 + O(x^5). (End)

Extensions

Definition corrected by Philippe Deléham, Dec 26 2013

A164851 Generalized Lucas-Pascal triangle; (11*10^n, 1).

Original entry on oeis.org

1, 11, 1, 110, 12, 1, 1100, 122, 13, 1, 11000, 1222, 135, 14, 1, 110000, 12222, 1357, 149, 15, 1, 1100000, 122222, 13579, 1506, 164, 16, 1, 11000000, 1222222, 135801, 15085, 1670, 180, 17, 1
Offset: 0

Views

Author

Mark Dols, Aug 28 2009

Keywords

Examples

			Triangle begins:
         1;
        11,      1;
       110,     12,      1;
      1100,    122,     13,     1;
     11000,   1222,    135,    14,    1;
    110000,  12222,   1357,   149,   15,   1;
   1100000, 122222,  13579,  1506,  164,  16,  1;
  11000000,1222222, 135801, 15085, 1670, 180, 17, 1;
  ...
		

Crossrefs

Programs

  • Maple
    G[0]:= 1;
    G[1]:= 11+x;
    G[2]:= 110+12*x+x^2;
    for nn from 3 to 20 do
      G[nn]:= expand((x+11)*G[nn-1]-10*(x+1)*G[nn-2]);
    od:
    seq(seq(coeff(G[n],x,j),j=0..n),n=0..20); # Robert Israel, Jul 17 2017
  • Mathematica
    T[0, 0] := 1; T[n_, n_] := 1; T[n_, 0] := 11*10^(n - 1); T[n_, k_] := T[n - 1, k - 1] + T[n - 1, k];  Table[T[n, k], {n, 0, 10}, {k, 0, n}] //Flatten (* G. C. Greubel, Dec 22 2017 *)

Formula

T(0,0)=1, T(n+1,0)=11*10^n, T(n,n)=1, T(n,k)=T(n-1,k-1)+T(n-1,k) for 0Philippe Deléham, Dec 27 2013
G.f. as triangle: (1-x^2)/((1-10*x)*(1-x-x*y)). - Robert Israel, Jul 17 2017

Extensions

Initial 1 added by Philippe Deléham, Dec 27 2013

A164899 Binomial matrix (1,10^n) read by antidiagonals.

Original entry on oeis.org

1, 1, 10, 1, 11, 100, 1, 12, 110, 1000, 1, 13, 121, 1100, 10000, 1, 14, 133, 1210, 11000, 100000, 1, 15, 146, 1331, 12100, 110000, 1000000, 1, 16, 160, 1464, 13310, 121000, 1100000, 10000000, 1, 17, 175, 1610, 14641, 133100, 1210000, 11000000, 100000000
Offset: 1

Views

Author

Mark Dols, Aug 30 2009

Keywords

Examples

			Matrix array, A(n, k), begins:
  1, 10, 100, 1000, ...
  1, 11, 110, 1100, ...
  1, 12, 121, 1210, ...
  1, 13, 133, 1331, ...
  1, 14, 146, 1464, ...
  1, 15, 160, 1610, ...
Antidiagonal triangle, T(n, k), begins as:
  1;
  1, 10;
  1, 11, 100;
  1, 12, 110, 1000;
  1, 13, 121, 1100, 10000;
  1, 14, 133, 1210, 11000, 100000;
  1, 15, 146, 1331, 12100, 110000, 1000000;
		

Crossrefs

Cf. A094704 (antidiagonal row sums).

Programs

  • Magma
    function T(n,k) // T = A164899
      if k eq n then return 10^(n-1);
      elif k eq 1 then return 1;
      else return T(n-1,k) + T(n-2,k-1);
      end if; return T;
    end function;
    [T(n,k): k in [1..n], n in [1..15]]; // G. C. Greubel, Feb 10 2023
    
  • Mathematica
    T[n_, k_]:= T[n,k]= If[k==n, 10^(n-1), If[k==1, 1, T[n-1,k] +T[n-2, k-1]]];
    Table[T[n, k], {n,15}, {k,n}]//Flatten (* G. C. Greubel, Feb 10 2023 *)
  • SageMath
    def T(n,k): # T = A164899
        if (k==n): return 10^(n-1)
        elif (k==1): return 1
        else: return T(n-1,k) + T(n-2,k-1)
    flatten([[T(n,k) for k in range(1,n+1)] for n in range(1,16)]) # G. C. Greubel, Feb 10 2023

Formula

Sum_{k=1..n} T(n, k) = A094704(n).
As a triangle T(n,k) read by rows, T(n,1) = 1, T(n,n) = 10^(n-1), and T(n,k) = T(n-1, k) + T(n-2, k-1) otherwise. - Joerg Arndt, Dec 10 2016
From G. C. Greubel, Feb 10 2023: (Start)
A(n, k) = A(n-1, k) + A(n-1, k-1), with A(n, 1) = 1 and A(1, k) = 10^(k-1) (array).
T(n, k) = A(n-k+1, k) (antidiagonal triangle). (End)

A164854 Diagonal sum of generalized Pascal triangle; (10^n,1).

Original entry on oeis.org

1, 1, 11, 12, 113, 125, 1138, 1263, 11401, 12664, 114065, 126729, 1140794, 1267523, 11408317, 12675840, 114084157, 126759997, 1140844154, 1267604151, 11408448305, 12676052456, 114084500761, 126760553217, 1140845053978, 1267605607195, 11408450661173
Offset: 0

Views

Author

Mark Dols, Aug 28 2009

Keywords

Crossrefs

Programs

  • Maple
    f:= gfun:-rectoproc({10*a(n-4)+10*a(n-3)-11*a(n-2)-a(n-1)+a(n),
    a(0)=1,a(1)=1,a(2)=11,a(3)=12},a(n),remember):
    map(f, [$0..30]); # Robert Israel, Jul 01 2016
  • Mathematica
    LinearRecurrence[{1,11,-10,-10},{1,1,11,12},30] (* Harvey P. Dale, Apr 07 2022 *)

Formula

From Robert Israel, Jul 01 2016: (Start)
G.f.: (1-x^2)/((1-10*x^2)*(1-x-x^2)).
a(n) = (171-9*(-1)^n)*10^floor(n/2)/142 + (A000045(n)-10*A000045(n+2))/71. (End)
a(n) = a(n-1)+11*a(n-2)-10*a(n-3)-10*a(n-4). - Wesley Ivan Hurt, Apr 21 2021

Extensions

More terms from Harvey P. Dale, Apr 07 2022
Showing 1-8 of 8 results.