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.

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A122104 Triangle read by rows: T(n,k) is the number of deco polyominoes of height n and such that the sum of the bottom levels of all columns is k (n>=1, k>=0; informally, the number of the "missing" cells in the right bottom corner of the polyomino). A deco polyomino is a directed column-convex polyomino in which the height, measured along the diagonal, is attained only in the last column.

Original entry on oeis.org

1, 2, 5, 1, 16, 5, 3, 65, 23, 20, 10, 2, 326, 119, 115, 84, 57, 11, 8, 1957, 719, 714, 582, 526, 310, 137, 55, 34, 6, 13700, 5039, 5033, 4222, 4173, 3291, 2506, 972, 748, 348, 220, 38, 30, 109601, 40319, 40312, 34026, 34454, 29792, 28055, 18723, 10613, 6745
Offset: 1

Views

Author

Emeric Deutsch, Aug 24 2006

Keywords

Comments

Row n has 1+floor((n-1)^2/4) terms. Row sums are the factorials (A000142). T(n,0)=A000522(n-1). T(n,1)=(n-1)!-1=A033312(n-1). T(n,2)=(n-1)!-n+1=A005096(n-1) for n>=2. Sum(k*T(n,k), k>=0)=A122105(n).

Examples

			Triangle starts:
1;
2;
5,1;
16,5,3;
65,23,20,10,2;
326,119,115,84,57,11,8;
		

References

  • E. Barcucci, S. Brunetti and F. Del Ristoro, Succession rules and deco polyominoes, Theoret. Informatics Appl., 34, 2000, 1-14.
  • E. Barcucci, A. Del Lungo and R. Pinzani, "Deco" polyominoes, permutations and random generation, Theoretical Computer Science, 159, 1996, 29-42.

Crossrefs

Programs

  • Maple
    Q[1]:=x: for n from 2 to 10 do Q[n]:=simplify(subs(x=t*x,Q[n-1])/t+(n-1)*x*Q[n-1]) od: for n from 1 to 10 do P[n]:=sort(subs(x=1,Q[n])) od: for n from 1 to 10 do seq(coeff(P[n],t,j),j=0..floor((n-1)^2/4)) od; # yields sequence in triangular form

Formula

The row generating polynomials P[n](t) are given by P[n](t)=Q[n](t,1), where Q[1](t,x)=x and Q[n](t,x) = (1/t)Q[n-1](t,tx)+(n-1)xQ[n-1](t,x) for n>=2.

Extensions

Keyword tabf added by Michel Marcus, Apr 09 2013

A196739 a(n) = n! - n^10.

Original entry on oeis.org

1, 0, -1022, -59043, -1048552, -9765505, -60465456, -282470209, -1073701504, -3486421521, -9996371200, -25897507801, -61438362624, -131631471049, -202076363776, 731023977375, 19823278260224, 353671434195551, 6398803238501376, 121638969342574199, 2432891768176640000
Offset: 0

Views

Author

Vincenzo Librandi, Oct 06 2011

Keywords

Crossrefs

Programs

  • Magma
    [Factorial(n)-n^10: n in [0..20]];
  • Mathematica
    Table[n!-n^10,{n,0,20}] (* Harvey P. Dale, May 19 2012 *)

A262376 a(n) = Sum_{k=0..n} (k! - k).

Original entry on oeis.org

1, 1, 1, 4, 24, 139, 853, 5886, 46198, 409069, 4037859, 43954648, 522956236, 6749977023, 93928268209, 1401602636194, 22324392524178, 378011820620161, 6780385526348143, 128425485935180124, 2561327494111820104, 53652269665821260083, 1177652997443428940061
Offset: 0

Views

Author

Daniel Suteu, Sep 20 2015

Keywords

Examples

			a(3) = 4, which is the following sum: (0!-0) + (1!-1) + (2!-2) + (3!-3).
		

Crossrefs

Partial sums of A005096.

Programs

  • Mathematica
    Table[Sum[k! - k, {k, 0, n}], {n, 0, 22}] (* Michael De Vlieger, Sep 21 2015 *)
  • PARI
    a(n)=sum(i=0,n,i!-i) \\ Anders Hellström, Sep 20 2015
  • Sidef
    var sum = 0;
    range(0, 10).each { |n|
        sum += (n! - n);
        say(n, "\t", sum);
    };
    

Formula

a(n) = Sum_{k=0..n} k! - k.
a(n) = A003422(n+1) - A000217(n). - Altug Alkan, Sep 20 2015

A141693 Triangle read by rows: T(n,k) = (2*k - n)*A008292(n,k) with T(n,n) = n, 0 <= k <= n, where A008292 is the triangle of Eulerian numbers.

Original entry on oeis.org

0, -1, 1, -2, 0, 2, -3, -4, 1, 3, -4, -22, 0, 2, 4, -5, -78, -66, 26, 3, 5, -6, -228, -604, 0, 114, 4, 6, -7, -600, -3573, -2416, 1191, 360, 5, 7, -8, -1482, -17172, -31238, 0, 8586, 988, 6, 8, -9, -3514, -73040, -264702, -156190, 88234, 43824, 2510, 7, 9, -10
Offset: 0

Views

Author

Roger L. Bagula, Sep 09 2008

Keywords

Examples

			Triangle begins:
    0;
   -1,     1;
   -2,     0,      2;
   -3,    -4,      1,       3;
   -4,   -22,      0,       2,       4;
   -5,   -78,    -66,      26,       3,     5;
   -6,  -228,   -604,       0,     114,     4,    6;
   -7,  -600,  -3573,   -2416,    1191,   360,    5,     7;
   -8, -1482, -17172,  -31238,       0,  8586,  988,     6, 8;
   -9, -3514, -73040, -264702, -156190, 88234, 43824, 2510, 7, 9;
  ...
		

Crossrefs

Cf. A008292.

Programs

  • Maple
    T:= proc(n,k) `if`(n=k,n,(2*k-n)*add((-1)^j*(k-j+1)^n*binomial(n+1,j),j=0..k)); end proc: seq(seq(T(n,k),k=0..n),n=0..10); # Muniru A Asiru, Oct 06 2018
    T := (n, k) -> `if`(n = k, n, (2*k - n)*combinat:-eulerian1(n,k)):
    seq(seq(T(n,k), k=0..n), n=0..9); # Peter Luschny, Oct 06 2018
  • Mathematica
    T[n_, k_] = If[n == k, n, (2*k - n)*Sum[(-1)^j*(k - j + 1)^n*Binomial[n + 1, j], {j, 0, k}]];
    Table[Table[T[n, k], {k, 0, n}], {n, 0, 10}]//Flatten
  • Maxima
    T(n, k) := if n = k then n else (2*k - n)*sum((-1)^j*(k - j + 1)^n*binomial(n + 1, j), j, 0, k)$
    tabl(nn) := for n:0 thru nn do print(makelist(T(n, k), k, 0, n))$ /* Franck Maminirina Ramaharo, Oct 05 2018 */

Formula

Sum_{k=0..n} T(n,k) = A005096(n), n > 0.
From Franck Maminirina Ramaharo, Oct 06 2018: (Start)
T(n,k) = (2*k - n)*Sum_{j=0..k} (-1)^j*(k - j + 1)^n*binomial(n + 1, j) for 0 <= k <= n - 1 and T(n,n) = n.
T(2*n-1,n-1) = -A025585(n).
T(2*n,n-1) = -A177042(n). (End)

Extensions

Edited, new name and offset corrected by Franck Maminirina Ramaharo, Oct 06 2018

A267897 a(n) = prime(n)! - prime(n).

Original entry on oeis.org

0, 3, 115, 5033, 39916789, 6227020787, 355687428095983, 121645100408831981, 25852016738884976639977, 8841761993739701954543615999971, 8222838654177922817725562879999969, 13763753091226345046315979581580902399999963
Offset: 1

Views

Author

Vincenzo Librandi, Jan 22 2016

Keywords

Crossrefs

Programs

  • Magma
    [Factorial(p)-p: p in PrimesUpTo(40)];
    
  • Mathematica
    Array[Prime[#]! - Prime[#] &, 20]
    #!-#&/@Prime[Range[20]] (* Harvey P. Dale, Oct 23 2024 *)
  • PARI
    lista(nn) = forprime(p=2, nn, print1(p! - p, ", ")); \\ Altug Alkan, Jan 23 2016

Formula

a(n) = A039716(n) - A000040(n).
a(n) = A005096(A000040(n)).
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