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 1-4 of 4 results.

A074825 Binomial transform of reflected pentanacci numbers A074062: a(n) = Sum_{k=0..n} binomial(n,k)*A074062(k).

Original entry on oeis.org

5, 4, 2, -2, -10, -16, -4, 46, 142, 250, 262, 4, -652, -1530, -1818, 38, 5662, 14760, 22028, 15014, -22490, -95846, -172434, -154740, 110500, 733134, 1556206, 1875238, 365334, -4306496, -11734244, -17112802, -9496002, 25050298, 90586134, 157886356, 142006676, -87803882
Offset: 0

Views

Author

Mario Catalani (mario.catalani(AT)unito.it), Sep 09 2002

Keywords

Crossrefs

Cf. A074062.

Programs

  • Magma
    I:=[5,4,2,-2,-10]; [n le 5 select I[n] else 4*Self(n-1) -7*Self(n-2) +6*Self(n-3) -3*Self(n-4) +2*Self(n-5): n in [1..51]]; // G. C. Greubel, Jul 05 2021
    
  • Mathematica
    CoefficientList[Series[(5-16x+21x^2-12x^3+3x^4)/(1-4x+7x^2-6x^3+3x^4-2x^5), {x, 0, 40}], x]
    LinearRecurrence[{4,-7,6,-3,2},{5,4,2,-2,-10},40] (* Harvey P. Dale, Nov 29 2019 *)
  • Sage
    def A074825_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( (5-16*x+21*x^2-12*x^3+3*x^4)/(1-4*x+7*x^2-6*x^3+3*x^4-2*x^5) ).list()
    A074825_list(50) # G. C. Greubel, Jul 05 2021

Formula

a(n) = 4*a(n-1) - 7*a(n-2) + 6*a(n-3) - 3*a(n-4) + 2*a(n-5), a(0)=5, a(1)=4, a(2)=2, a(3)=-2, a(4)=-10.
G.f.: (5 -16*x +21*x^2 -12*x^3 +3*x^4)/(1 -4*x +7*x^2 -6*x^3 +3*x^4 -2*x^5).

A074826 Binomial transform of reflected pentanacci numbers A074062: a(n) = Sum_{k=0..n}(-1)^k*binomial(n, k)*A074062(k).

Original entry on oeis.org

5, 6, 6, 6, 6, -4, -60, -246, -722, -1758, -3754, -7144, -11868, -15646, -9458, 32726, 174750, 555668, 1446564, 3310642, 6788406, 12366066, 19107358, 21047904, -1585148, -101419654, -400928730, -1155269658, -2838111242, -6203242964, -12144929980, -20857830310, -29087301442
Offset: 0

Views

Author

Mario Catalani (mario.catalani(AT)unito.it), Sep 10 2002

Keywords

Crossrefs

Programs

  • Magma
    R:=PowerSeriesRing(Integers(), 40);
    Coefficients(R!( (5-24*x+45*x^2-40*x^3+15*x^4)/(1-6*x+15*x^2-20*x^3+15*x^4 -4*x^5) )); // G. C. Greubel, Jul 08 2021
    
  • Mathematica
    CoefficientList[Series[(5-24x+45x^2-40x^3+15x^4)/(1-6x+15x^2-20x^3+15x^4-4x^5), {x, 0, 35}], x]
  • Sage
    def A168823_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( (5-24*x+45*x^2-40*x^3+15*x^4)/(1-6*x+15*x^2-20*x^3+15*x^4-4*x^5) ).list()
    A168823_list(40) # G. C. Greubel, Jul 08 2021

Formula

a(n) = Sum_{j=0..n} (-1)^j*binomial(n, j)*A074062(j)
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 4*a(n-5), a(0) = 5, a(1) = 6, a(2) = 6, a(3) = 6, a(4) = 6.
G.f.: (5 -24*x +45*x^2 -40*x^3 +15*x^4)/(1 -6*x +15*x^2 -20*x^3 +15*x^4 -4*x^5).

A001591 Pentanacci numbers: a(n) = a(n-1) + a(n-2) + a(n-3) + a(n-4) + a(n-5), a(0)=a(1)=a(2)=a(3)=0, a(4)=1.

Original entry on oeis.org

0, 0, 0, 0, 1, 1, 2, 4, 8, 16, 31, 61, 120, 236, 464, 912, 1793, 3525, 6930, 13624, 26784, 52656, 103519, 203513, 400096, 786568, 1546352, 3040048, 5976577, 11749641, 23099186, 45411804, 89277256, 175514464, 345052351, 678355061, 1333610936, 2621810068
Offset: 0

Views

Author

Keywords

Comments

Number of permutations satisfying -k <= p(i) - i <= r, i=1..n-4, with k=1, r=4. - Vladimir Baltic, Jan 17 2005
a(n) is the number of compositions of n-4 with no part greater than 5. - Vladimir Baltic, Jan 17 2005
The pentanomial (A035343(n)) transform of a(n) is a(5n+4), n >= 0. - Bob Selcoe, Jun 10 2014
a(n) is the number of ways to tile a strip of length n-4 with squares, dominoes, trominoes (of length 3), and rectangles with length 4 (tetraminoes) and length 5 (pentaminoes). - Wajdi Maaloul, Jun 21 2022

Examples

			n=2: a(14) = (1*1 + 2*1 + 3*2 + 4*4 + 5*8 + 4*16 + 3*31 + 2*61 + 1*120) = 464. - _Bob Selcoe_, Jun 10 2014
G.f. = x^4 + x^5 + 2*x^6 + 4*x^7 + 8*x^8 + 16*x^9 + 31*x^10 + 120*x^11 + ...
		

References

  • Silvia Heubach and Toufik Mansour, Combinatorics of Compositions and Words, CRC Press, 2010.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Row 5 of arrays A048887 and A092921 (k-generalized Fibonacci numbers).
Cf. A106303 (Pisano period lengths).
Cf. A035343 (pentanomial coefficients).

Programs

  • Magma
    a:=[0,0,0,0,1]; [n le 5 select a[n] else Self(n-1) + Self(n-2) + Self(n-3) + Self(n-4) + Self(n-5): n in [1..40]]; // Marius A. Burtea, Oct 03 2019
    
  • Maple
    g:=1/(1-z-z^2-z^3-z^4-z^5): gser:=series(g, z=0, 49): seq((coeff(gser, z, n)), n=-4..32); # Zerinvary Lajos, Apr 17 2009
    # second Maple program:
    a:= n-> (<<0|1|0|0|0>, <0|0|1|0|0>, <0|0|0|1|0>, <0|0|0|0|1>, <1|1|1|1|1>>^n)[1, 5]:
    seq(a(n), n=0..44);  # Alois P. Heinz, Apr 09 2021
  • Mathematica
    CoefficientList[Series[x^4/(1 - x - x^2 - x^3 - x^4 - x^5), {x, 0, 50}], x]
    a[0] = a[1] = a[2] = a[3] = 0; a[4] = a[5] = 1; a[n_] := a[n] = 2 a[n - 1] - a[n - 6]; Array[a, 37, 0]
    LinearRecurrence[{1, 1, 1, 1, 1}, {0, 0, 0, 0, 1}, 50] (* Vladimir Joseph Stephan Orlovsky, May 25 2011 *)
  • Maxima
    a(n):=mod(floor(10^((n-4)*(n+1))*10^(5*(n+1))*(10^(n+1)-1)/(10^(6*(n+1))-2*10^(5*(n+1))+1)),10^n); /* Tani Akinari, Apr 10 2014 */
    
  • PARI
    a=vector(100);a[4]=a[5]=1;for(n=6,#a,a[n]=a[n-1]+a[n-2]+a[n-3]+a[n-4]+a[n-5]);concat(0, a) \\ Charles R Greathouse IV, Jul 15 2011
    
  • PARI
    A001591(n,m=5)=(matrix(m,m,i,j,i==j-1||i==m)^n)[1,m] \\ M. F. Hasler, Apr 20 2018
    
  • PARI
    a(n)= {my(x='x, p=polrecip(1 - x - x^2 - x^3 - x^4 - x^5)); polcoef(lift(Mod(x, p)^n), 4); }
    vector(41, n, a(n-1)) \\ Joerg Arndt, May 16 2021
    
  • Python
    def pentanacci():
        a, b, c, d, e = 0, 0, 0, 0, 1
        while True:
            yield a
            a, b, c, d, e = b, c, d, e, a + b + c + d + e
    f = pentanacci()
    print([next(f) for  in range(100)]) # _Reza K Ghazi Apr 09 2021

Formula

G.f.: x^4/(1 - x - x^2 - x^3 - x^4 - x^5). - Simon Plouffe in his 1992 dissertation.
G.f.: Sum_{n >= 0} x^(n+4) * (Product_{k = 1..n} (k + k*x + k*x^2 + k*x^3 + x^4)/(1 + k*x + k*x^2 + k*x^3 + k*x^4)). - Peter Bala, Jan 04 2015
Another form of the g.f.: f(z) = (z^4-z^5)/(1-2*z+z^6); then a(n) = Sum_{i=0..floor((n-4)/6)} ((-1)^i*binomial(n-4-5*i,i)*2^(n-4-6*i)) - Sum_{i=0..floor((n-5)/6)} ((-1)^i*binomial(n-5-5*i,i)*2^(n-5-6*i)) with convention Sum_{i=m..n} alpha(i) = 0 for m > n. - Richard Choulet, Feb 22 2010
a(n) = Sum_{k=1..n} (Sum_{r=0..k} (binomial(k,r) * Sum_{m=0..r} (binomial(r,m) * Sum_{j=0..m} (binomial(m,j)*binomial(j,n-m-k-j-r))))), n > 0. - Vladimir Kruchinin, Aug 30 2010
Sum_{k=0..4*n} a(k+b)*A035343(n,k) = a(5*n+b), b >= 0.
a(n) = 2*a(n-1) - a(n-6). - Vincenzo Librandi, Dec 19 2010
a(n) = (Sum_{i=0..n-1} a(i)*A074048(n-i))/(n-4) for n > 4. - Greg Dresden and Advika Srivastava, Oct 01 2019
For k>0 and n>0, a(n+5*k) = A074048(k)*a(n+4*k) - A123127(k-1)*a(n+3*k) + A123126(k-1)*a(n+2*k) - A074062(k)*a(n+k) + a(n). - Kai Wang, Sep 06 2020
lim n->oo a(n)/a(n-1) = A103814. - R. J. Mathar, Mar 11 2024

A074048 Pentanacci numbers with initial conditions a(0)=5, a(1)=1, a(2)=3, a(3)=7, a(4)=15.

Original entry on oeis.org

5, 1, 3, 7, 15, 31, 57, 113, 223, 439, 863, 1695, 3333, 6553, 12883, 25327, 49791, 97887, 192441, 378329, 743775, 1462223, 2874655, 5651423, 11110405, 21842481, 42941187, 84420151, 165965647, 326279871, 641449337, 1261056193, 2479171199, 4873922247
Offset: 0

Views

Author

Mario Catalani (mario.catalani(AT)unito.it), Aug 14 2002

Keywords

Comments

These pentanacci numbers follow the same pattern as Lucas, generalized tribonacci(A001644) and generalized tetranacci (A073817) numbers: Binet's formula is a(n)=r1^n+r^2^n+r3^n+r4^n+r5^n, with r1, r2, r3, r4, r5 roots of the characteristic polynomial. a(n) is also the trace of A^n, where A is the pentamatrix ((1,1,0,0,0),(1,0,1,0,0),(1,0,0,1,0),(1,0,0,0,1),(1,0,0,0,0)).
For n >= 5, a(n) is the number of cyclic sequences consisting of n zeros and ones that do not contain five consecutive ones provided the positions of the zeros and ones are fixed on a circle. This is proved in Charalambides (1991) and Zhang and Hadjicostas (2015). (For n=1,2,3,4 the statement is still true provided we allow the sequence to wrap around itself on a circle). - Petros Hadjicostas, Dec 18 2016
a(3407) has 1001 decimal digits. - Michael De Vlieger, Dec 28 2016

Crossrefs

Cf. A000078, A001630, A001644, A000032, A073817, A106297 (Pisano Periods).
Essentially the same as A023424.
Cf. A106273.

Programs

  • Mathematica
    CoefficientList[Series[(5-4*x-3*x^2-2*x^3-x^4)/(1-x-x^2-x^3-x^4-x^5), {x, 0, 30}], x]
    LinearRecurrence[{1, 1, 1, 1, 1}, {5, 1, 3, 7, 15}, 60] (* Vladimir Joseph Stephan Orlovsky, Feb 08 2012 *)
  • PARI
    polsym(polrecip(1-x-x^2-x^3-x^4-x^5),33) \\ Joerg Arndt, Jan 28 2019

Formula

a(n) = a(n-1) +a(n-2) +a(n-3) +a(n-4) +a(n-5).
G.f.: (5-4*x-3*x^2-2*x^3-x^4) / (1-x-x^2-x^3-x^4-x^5).
a(n) = 2*a(n-1) -a(n-6), n>5. [Vincenzo Librandi, Dec 20 2010]
For k>0 and n>=0, a(n+5*k) = a(k)*a(n+4*k) - A123127(k-1)*a(n+3*k) + A123126(k-1)*a(n+2*k) - A074062(k)*a(n+k) + a(n). For example, if k=4, n=3, we have a(n+5*k) = a(23) = 5651423, a(4)*a(19) - A123127(3)*a(15) + A123126(3)*a(1695) - A074062(4)*a(7) + a(3) = (15)*(378329) - (1)*(25327) + (1)*(1695) - (-1)*(113) + (7) = 5651423. - Kai Wang, Sep 13 2020
From Kai Wang, Dec 16 2020: (Start)
For k >= 0,
| a(k+4) a(k+5) a(k+6) a(k+7) a(k+8) |
| a(k+3) a(k+4) a(k+5) a(k+6) a(k+7) |
det | a(k+2) a(k+3) a(k+4) a(k+5) a(k+6) | = 9584 = A106273(5).
| a(k+1) a(k+2) a(k+3) a(k+4) a(k+5) |
| a(k) a(k+1) a(k+2) a(k+3) a(k+4) |
(End)
Showing 1-4 of 4 results.