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.

A231182 Coefficients for the nonnegative powers of rho(11) = 2*cos(Pi/11) when written in the power basis of the degree 5 number field Q(rho(11)). Coefficients for the zeroth and fourth powers.

Original entry on oeis.org

1, 0, 0, 0, 0, 1, 1, 5, 6, 20, 27, 75, 110, 275, 429, 1001, 1637, 3639, 6172, 13243, 23104, 48280, 86090, 176341, 319792, 645150, 1185305, 2363596, 4386331, 8669142, 16212913, 31825005, 59873834, 116914020, 220964744, 429737220, 815057639
Offset: 0

Views

Author

Wolfdieter Lang, Nov 05 2013

Keywords

Comments

The formula for rho(11)^n, with rho(11) = 2*cos(Pi/11) (the length ratio (smallest diagonal)/side in the regular 11-gon) written in the power basis of the number field Q(rho(11)) is: rho(11)^n = a(n)*1 - A231183(n)*rho(11) - A231184(n-2)* rho(11)^2 + A231185(n-3)*rho(11)^3 + a(n+1)*rho(11)^4, n >= 0.

Examples

			rho(11)^4 = 0*1 - 0*rho(11) - 0*rho(11)^2 + 0*rho(11)^3 + 1*rho(11)^4 (trivial).
rho(11)^5 = 1*1 - 3*rho(11) - 3*rho(11)^2 + 4*rho(11)^3 + 1*rho(11)^4. Approximately 26.02309649, with rho(11) approximately 1.918985947.
		

Crossrefs

Formula

G.f.: (1-x-x^2)*(1-3*x^2)/(1-x-4*x^2+3*x^3+3*x^4-x^5).
a(n) = a(n-1) + 4*a(n-2) - 3*a(n-3) - 3*a(n-4) + a(n-5) for n>= 5, with a(0)=1, a(1)=a(2)=a(3)=a(4)=0.
a(n) = b(n) - b(n-1) - 4*b(n-2) + 3*b(n-3) + 3*b(n-4) for n>=0, with b(n) = A231181(n).

A231183 Coefficients of the nonnegative powers of rho(11) = 2*cos(Pi/11) when written in the power basis of the degree 5 number field Q(rho(11)). Negative of the coefficients of the first power.

Original entry on oeis.org

0, -1, 0, 0, 0, 3, 2, 14, 13, 54, 61, 198, 255, 715, 1012, 2574, 3910, 9280, 14877, 33557, 56069, 121736, 209990, 442933, 783035, 1615658, 2910765, 5905483, 10795397, 21621095, 39969597, 79262102, 147796497, 290868226, 545980212, 1068246916
Offset: 0

Views

Author

Wolfdieter Lang, Nov 07 2013

Keywords

Comments

The formula for rho(11)^n is (see A231182): rho(11)^n = A231182(n)*1 - a(n)*rho(11) - A231184(n-2)*rho(11)^2 + A231185(n-3)*rho(11)^3 + A231182(n+1)*rho(11)^4, n >= 0.

Examples

			rho(11)^5 = 1*1 - 3*rho(11) - 3*rho(11)^2 + 4*rho(11)^3 + 1*rho(11)^4. Approximately 26.02309649, with rho(11) approximately 1.918985947.
		

Crossrefs

Formula

G.f.: x*(-1 + x + 4*x^2 -3*x^3)/(1-x-4*x^2+3*x^3+3*x^4-x^5).
a(n) = a(n-1) + 4*a(n-2) - 3*a(n-3) - 3*a(n-4) + a(n-5) for n >= 5, with a(0)=0, a(1)=-1, a(2)=a(3)=a(4)=0.
a(n) = -b(n-1) + b(n-2) + 4*b(n-3) - 3*b(n-4) for n>=0, with b(n) = A231181(n).

A231184 Coefficients of the nonnegative powers of rho(11) = 2*cos(Pi/11) when written in the power basis of the degree 5 number field Q(rho(11)). Negative of the coefficients of the second power.

Original entry on oeis.org

-1, 0, 0, 3, 6, 17, 32, 73, 135, 286, 528, 1080, 2002, 4015, 7485, 14827, 27796, 54606, 102869, 200909, 380006, 739013, 1402309, 2718485, 5171573, 10001553, 19064476, 36802823, 70259834, 135444612, 258883604, 498538557, 953762458
Offset: 0

Views

Author

Wolfdieter Lang, Nov 07 2013

Keywords

Comments

The formula for rho(11)^n is (see A231182): rho(11)^n = A231182(n)*1 - A231183(n)*rho(11) - a(n-2)*rho(11)^2 + A231185(n-3)*rho(11)^3 + A231182(n+1)*rho(11)^4, n >= 0.

Examples

			rho(11)^5 = 1*1 - 3*rho(11) - 3*rho(11)^2 + 4*rho(11)^3 + 1*rho(11)^4. Approximately 26.02309649, with rho(11) approximately 1.918985947.
		

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{1,4,-3,-3,1},{-1,0,0,3,6},40] (* Harvey P. Dale, Apr 26 2019 *)

Formula

G.f.: (-1 + x + 4*x^2)/(1-x-4*x^2+3*x^3+3*x^4-x^5).
a(n) = a(n-1) + 4*a(n-2) - 3*a(n-3) - 3*a(n-4) + a(n-5) for n >= 3, with a(-2)=a(-1)=0 , a(0)=-1, a(1)=a(2)=0.
a(n) = -b(n) + b(n-1) + 4*b(n-2), n>=0, with b(n) = A231181(n).

A231185 Coefficients of the nonnegative powers of rho(11) = 2*cos(Pi/11) when written in the power basis of the degree 5 number field Q(rho(11)). Coefficients of the third power.

Original entry on oeis.org

1, 0, 4, 1, 14, 7, 48, 35, 165, 154, 572, 636, 2002, 2533, 7071, 9861, 25176, 37810, 90251, 143451, 325358, 540155, 1178291, 2022735, 4282811, 7543771, 15612092, 28048829, 57040186, 104050724, 208772476, 385320419, 765186422, 1425038684
Offset: 0

Views

Author

Wolfdieter Lang, Nov 07 2013

Keywords

Comments

This sequence gives the first differences of A231181.
The formula for rho(11)^n is (see A231182): rho(11)^n = A231182(n)*1 - A231183(n)*rho(11) - A231184(n-2)*rho(11)^2 + a(n-3)*rho(11)^3 + A231182(n+1)*rho(11)^4, n >= 0.

Examples

			rho(11)^5 = 1*1 - 3*rho(11) - 3*rho(11)^2 + 4*rho(11)^3 + 1*rho(11)^4. Approximately 26.02309649, with rho(11) approximately 1.918985947.
		

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{1,4,-3,-3,1},{1,0,4,1,14},40] (* Harvey P. Dale, Aug 03 2023 *)

Formula

G.f.: (1 - x)/(1-x-4*x^2+3*x^3+3*x^4-x^5).
a(n) = a(n-1) + 4*a(n-2) - 3*a(n-3) - 3*a(n-4) + a(n-5) for n >= 0, with a(-5)=-2, a(-4)=-1 , a(-3)=a(-2)=a(-1)=0.
a(n) = b(n) - b(n-1) for n>=0, with b(n) = A231181(n) (first differences).

A309896 Generalized Fibonacci numbers. Square array read by ascending antidiagonals. F(n,k) for n >= 0 and k >= 0.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 2, 1, 0, 1, 1, 3, 3, 1, 0, 1, 1, 4, 4, 5, 1, 0, 1, 1, 5, 5, 9, 8, 1, 0, 1, 1, 6, 6, 14, 14, 13, 1, 0, 1, 1, 7, 7, 20, 20, 28, 21, 1, 0, 1, 1, 8, 8, 27, 27, 48, 47, 34, 1, 0, 1, 1, 9, 9, 35, 35, 75, 75, 89, 55, 1, 0
Offset: 0

Views

Author

Peter Luschny, Aug 21 2019

Keywords

Examples

			Array starts:
[0] 1, 0, 0,  0,  0,  0,   0,   0,    0,    0,    0,    0, ...
[1] 1, 1, 1,  1,  1,  1,   1,   1,    1,    1,    1,    1, ...
[2] 1, 1, 2,  3,  5,  8,  13,  21,   34,   55,   89,  144, ...
[3] 1, 1, 3,  4,  9, 14,  28,  47,   89,  155,  286,  507, ...
[4] 1, 1, 4,  5, 14, 20,  48,  75,  165,  274,  571,  988, ...
[5] 1, 1, 5,  6, 20, 27,  75, 110,  275,  429, 1001, 1637, ...
[6] 1, 1, 6,  7, 27, 35, 110, 154,  429,  637, 1638, 2548, ...
[7] 1, 1, 7,  8, 35, 44, 154, 208,  637,  910, 2548, 3808, ...
[8] 1, 1, 8,  9, 44, 54, 208, 273,  910, 1260, 3808, 5508, ...
[9] 1, 1, 9, 10, 54, 65, 273, 350, 1260, 1700, 5508, 7752, ...
		

Crossrefs

Cf. A000007 (n=0), A000012 (n=1), A000045 (n=2), A006053 (n=3), A188021 (n=4), A231181 (n=5).

Programs

  • SageMath
    @cached_function
    def F(n, k):
        if k <  0: return 0
        if k == 0: return 1
        a = sum((-1)^j*binomial(n-1-j,j  )*F(n,k-1-2*j) for j in (0..(n-1)/2))
        b = sum((-1)^j*binomial(n-1-j,j+1)*F(n,k-2-2*j) for j in (0..(n-2)/2))
        return a + b
    print([F(n-k, k) for n in (0..11) for k in (0..n)])

Formula

F(n, k) = Sum_{j=0..(n-1)/2} (-1)^j*binomial(n-1-j,j)*F(n, k-1-2*j) + Sum_{j=0..(n-2)/2} (-1)^j*binomial(n-1-j, j+1)*F(n, k-2-2*j) for k > 0; F(n, 0) = 1 and F(n, k) = 0 if k < 0.
Showing 1-5 of 5 results.