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 1-5 of 5 results.

A051163 Sequence is defined by property that (a0,a1,a2,a3,...) = binomial transform of (a0,a0,a1,a1,a2,a2,a3,a3,...).

Original entry on oeis.org

1, 2, 5, 12, 30, 76, 194, 496, 1269, 3250, 8337, 21428, 55184, 142376, 367916, 952000, 2466014, 6393372, 16586678, 43054344, 111801908, 290412296, 754543052, 1960808160, 5096293794, 13247503540, 34440553562, 89549255592, 232868582328, 605646682144
Offset: 0

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Author

Keywords

Comments

Equals the self-convolution of A027826. Also equals antidiagonal sums of symmetric square array A100936. - Paul D. Hanna, Nov 22 2004
Equals eigensequence of triangle A152198. - Gary W. Adamson, Nov 28 2008

Crossrefs

Programs

  • Maple
    a:= proc(n) option remember; add(`if`(k<2, 1,
          a(iquo(k, 2)))*binomial(n, k), k=0..n)
        end:
    seq(a(n), n=0..40);  # Alois P. Heinz, Jul 08 2015
  • Mathematica
    a[n_] := a[n] = 1 + Sum[Binomial[k, j]*Binomial[n-k, j]*a[j], {k, 1, n}, {j, 0, n-k}]; Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Nov 11 2015 *)
  • PARI
    a(n)=1+sum(k=1,n,sum(j=0,n-k,binomial(k,j)*binomial(n-k,j)*a(j)))
    
  • PARI
    a(n)=local(A,m); if(n<0,0,m=1; A=1+O(x); while(m<=n,m*=2; A=subst(A,x,(x/(1-x))^2)/(1-x)); polcoeff(A^2,n))
    for(n=0,40,print1(a(n),", ")) \\ Paul D. Hanna, Nov 22 2004

Formula

a(n) = 1 + Sum_{k=1..n} Sum_{j=0..n-k} C(k, j)*C(n-k, j)*a(j). - Paul D. Hanna, Nov 22 2004
G.f. A(x) satisfies: A(x) = A(x^2/(1-x)^2)/(1-x)^2 and A(x^2) = A(x/(1+x))/(1+x)^2. - Paul D. Hanna, Nov 22 2004
a(0) = 1; a(n) = Sum_{k=0..floor(n/2)} binomial(n+1,2*k+1) * a(k). - Ilya Gutkovskiy, Apr 07 2022

Extensions

More terms from Vladeta Jovovic, Jul 26 2002

A051165 Sequence is defined by property that binomial transform of (a0,a1,a2,a3,...) = (a0,a0,a1,a1,a2,a2,a3,a3,...).

Original entry on oeis.org

1, 0, -1, 2, -4, 8, -12, 8, 15, -56, 81, -26, -130, 208, 306, -2060, 4796, -5120, -6140, 43320, -113768, 182720, -111768, -395696, 1725172, -3922016, 5614348, -2289912, -14957416, 56700032, -121684568, 164735504, -47657969, -491084768, 1740799985, -3598600386, 4619098604
Offset: 0

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Author

Keywords

Crossrefs

Programs

  • Maple
    a:= proc(n) option remember; add(`if`(k<2, 1,
          a(iquo(k, 2)))*(-1)^(n-k)*binomial(n, k), k=0..n)
        end:
    seq(a(n), n=0..45);  # Alois P. Heinz, Jul 08 2015
  • Mathematica
    a[n_] := a[n] = Sum[If[k<2, 1, a[Quotient[k, 2]]]*(-1)^(n-k)*Binomial[n, k], {k, 0, n}];
    Table[a[n], {n, 0, 45}] (* Jean-François Alcover, Jun 04 2018, from Maple *)

Extensions

More terms from Vladeta Jovovic, Jul 26 2002

A051166 Sequence is defined by property that binomial transform of (a0,a1,a2,a3,...) = (a0,a0,a0,a1,a1,a1,a2,a2,a2,a3,a3,a3,...).

Original entry on oeis.org

1, 0, 0, -1, 3, -6, 10, -15, 21, -29, 45, -90, 224, -609, 1677, -4559, 12135, -31542, 80086, -199035, 485469, -1165105, 2757369, -6446778, 14913052, -34175805, 77672325, -175228740, 392711166, -874901088, 1938704130, -4275110880, 9385473510, -20521355211, 44704157499, -97055415324
Offset: 0

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Author

Keywords

Crossrefs

Programs

  • Maple
    a:= proc(n) option remember; add(`if`(k<3, 1,
          a(iquo(k, 3)))*(-1)^(n-k)*binomial(n, k), k=0..n)
        end:
    seq(a(n), n=0..45);  # Alois P. Heinz, Jul 08 2015
  • Mathematica
    a[n_] := a[n] = Sum[If[k<3, 1, a[Quotient[k, 3]]]*(-1)^(n-k)*Binomial[n, k], {k, 0, n}];
    Table[a[n], {n, 0, 45}] (* Jean-François Alcover, Apr 04 2017, after Alois P. Heinz *)

Extensions

More terms from Vladeta Jovovic, Jul 26 2002

A137256 Binomial transform of 2^n, 2^n, 2^n.

Original entry on oeis.org

1, 2, 4, 9, 21, 48, 108, 243, 549, 1242, 2808, 6345, 14337, 32400, 73224, 165483, 373977, 845154, 1909980, 4316409, 9754749, 22044960, 49819860, 112588947, 254442141, 575019162, 1299497904, 2936762649, 6636851721, 14998760928
Offset: 0

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Author

Paul Curtz, Mar 11 2008

Keywords

Comments

Sequence is identical to half its third differences.

References

  • Maribel Díaz Noguera [Maribel Del Carmen Díaz Noguera], Rigoberto Flores, Jose L. Ramirez, and Martha Romero Rojas, Catalan identities for generalized Fibonacci polynomials, Fib. Q., 62:2 (2024), 100-111. See Table 3.

Crossrefs

Programs

  • Magma
    I:=[1,2,4]; [n le 3 select I[n] else 3*(Self(n-1) -Self(n-2) +Self(n-3)): n in [1..30]]; // G. C. Greubel, Apr 10 2021
    
  • Maple
    m:=30; S:=series( (1-x+x^2)/(1-3*x+3*x^2-3*x^3), x, m+1):
    seq(coeff(S, x, j), j=0..m); # G. C. Greubel, Apr 10 2021
  • Mathematica
    LinearRecurrence[{3, -3, 3},{1, 2, 4},30] (* Ray Chandler, Sep 23 2015 *)
  • Sage
    def A137256_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( (1-x+x^2)/(1-3*x+3*x^2-3*x^3) ).list()
    A137256_list(30) # G. C. Greubel, Apr 10 2021

Formula

a(n) = 3*a(n-1) - 3*a(n-2) + 3*a(n-3).
O.g.f.: (1 -x +x^2)/(1 -3*x +3*x^2 -3*x^3). - R. J. Mathar, Apr 02 2008

Extensions

More terms from R. J. Mathar, Apr 02 2008

A059864 a(n) = Product_{i=4..n} (prime(i)-5), where prime(i) is i-th prime.

Original entry on oeis.org

1, 1, 1, 2, 12, 96, 1152, 16128, 290304, 6967296, 181149696, 5796790272, 208684449792, 7930009092096, 333060381868032, 15986898329665536, 863292509801938944, 48344380548908580864, 2997351594032332013568
Offset: 1

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Author

Labos Elemer, Feb 28 2001

Keywords

Comments

Such products arise in Hardy-Littlewood prime k-tuplet conjectural formulas.

References

  • Steven R. Finch, Mathematical Constants, Cambridge, 2003, pp. 84-94.
  • R. K. Guy, Unsolved Problems in Number Theory, A8, A1
  • G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers, 5th ed., Oxford Univ. Press, 1979.
  • G. Polya, Mathematics and Plausible Reasoning, Vol. II, Appendix Princeton UP, 1954

Crossrefs

Programs

  • Magma
    [n le 3 select 1 else (&*[NthPrime(j) -5: j in [4..n]]): n in [1..30]]; // G. C. Greubel, Feb 02 2023
    
  • Mathematica
    Join[{1,1,1},FoldList[Times,Prime[Range[4,20]]-5]] (* Harvey P. Dale, Dec 29 2018 *)
  • PARI
    a(n) = prod(k=4, n, prime(k)-5); \\ Michel Marcus, Dec 12 2017
    
  • SageMath
    def A059864(n): return product(nth_prime(j) -5 for j in range(4,n+1))
    [A059864(n) for n in range(1,31)] # G. C. Greubel, Feb 02 2023
Showing 1-5 of 5 results.