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 1-10 of 58 results. Next

A082480 a(n) = Product_{k=1..n} (F(k)+1) where F(k) denotes the k-th Fibonacci number.

Original entry on oeis.org

1, 2, 4, 12, 48, 288, 2592, 36288, 798336, 27941760, 1564738560, 140826470400, 20419838208000, 4778242140672000, 1806175529174016000, 1103573248325323776000, 1090330369345419890688000, 1742347930213980985319424000, 4503969399603140847050711040000
Offset: 0

Views

Author

Benoit Cloitre, Apr 27 2003

Keywords

Comments

Equals row sums (unsigned) of triangle A158472. - Gary W. Adamson, Mar 20 2009

Crossrefs

Cf. A000045, A158472. - Gary W. Adamson, Mar 20 2009

Programs

  • Maple
    with(combinat): a:= n->mul(fibonacci(j)+1, j=0..n): seq(a(n), n=0..20); # Zerinvary Lajos, Mar 29 2009
  • Mathematica
    Table[Product[Fibonacci[k]+1,{k,1,n}],{n,0,20}] (* Vaclav Kotesovec, Jul 19 2015 *)
  • PARI
    a(n)=prod(k=1,n,fibonacci(k)+1)

Formula

a(n) ~ f * C * ((1+sqrt(5))/2)^(n*(n+1)/2) / 5^(n/2), where C = A062073 = 1.2267420107203532444176302304553616558714096904402504196432973... is the Fibonacci factorial constant and f = Product_{k>=1} (1 + 1/Fibonacci(k)) = 13.150966657784184367612433370626658932190199543164284701354100747157698046... . - Vaclav Kotesovec, Jul 19 2015
Equals the obverse convolution of A000012 and A000045; see A374848. a(n) = (F(n)+1)*a(n-1) for n>=1, where F(n) = A000045(n) = n-th Fibonacci number. - Clark Kimberling, Aug 05 2024

A374880 Obverse convolution (floor(3n/2))**(floor(3n/2)); see Comments.

Original entry on oeis.org

0, 1, 18, 256, 5400, 117649, 3359232, 100000000, 3643149312, 137858491849, 6126151500000, 281474976710656, 14777503265582208, 799006685782884121, 48413259982080000000, 3011361496339065143296, 206882551397716479442944, 14551915228366851806640625
Offset: 0

Views

Author

Clark Kimberling, Jul 31 2024

Keywords

Comments

See A374848 for the definition of obverse convolution and a guide to related sequences. If k>=0, then a(2k) is even and a(2k+1) is a square.

Crossrefs

Programs

  • Mathematica
    s[n_] := Floor[3 n/2]; t[n_] := Floor[3 n/2];
    u[n_] := Product[s[k] + t[n - k], {k, 0, n}]
    Table[u[n], {n, 0, 24}]

Formula

a(n) ~ exp(-1/3) * (3*n/2)^(n+1). - Vaclav Kotesovec, Aug 02 2024

A374881 Obverse convolution (n)**(n^2); see Comments.

Original entry on oeis.org

0, 1, 16, 405, 15360, 818125, 58226688, 5332085577, 610140160000, 85235284359225, 14264819712000000, 2815701027697558429, 646960843646287478784, 171112492588968115453125, 51595090958399913852928000, 17587698619968027952119140625
Offset: 0

Views

Author

Clark Kimberling, Jul 31 2024

Keywords

Comments

See A374848 for the definition of obverse convolution and a guide to related sequences.

Crossrefs

Programs

  • Mathematica
    s[n_] := n; t[n_] := n^2;
    u[n_] := Product[s[k] + t[n - k], {k, 0, n}]
    Table[u[n], {n, 0, 18}]

Formula

a(n) ~ n^(2*n + 1) / exp(2*n + 1 - Pi*sqrt(n)). - Vaclav Kotesovec, Jul 31 2024

A375041 Irregular triangular array T; row n shows the coefficients of the (n-1)-st polynomial in the obverse convolution s(x)**t(x), where s(x) = n^2 x and t(x) = x+1. See Comments.

Original entry on oeis.org

1, 1, 1, 3, 2, 1, 8, 17, 10, 1, 18, 97, 180, 100, 1, 35, 403, 1829, 3160, 1700, 1, 61, 1313, 12307, 50714, 83860, 44200, 1, 98, 3570, 60888, 506073, 1960278, 3147020, 1635400, 1, 148, 8470, 239388, 3550473, 27263928, 101160920, 158986400, 81770000, 1, 213
Offset: 1

Views

Author

Clark Kimberling, Sep 11 2024

Keywords

Comments

See A374848 for the definition of obverse convolution and a guide to related sequences and arrays.

Examples

			First 3 polynomials in s(x)**t(x) are
  1 + x,
  1 + 3 x + 2 x^2,
  1 + 8 x + 17 x^2 + 10 x^3.
First 5 rows of array:
  1    1
  1    3     2
  1    8    17    10
  1   18    97   180   100
  1   35  4034  1829  3160  1700
		

Crossrefs

Cf. A000290, A081489 (column 2), A101686 (T(n,n+1)), A374848, A375042, A375043.

Programs

  • Mathematica
    s[n_] := n^2  x; t[n_] := 1 + x;
    u[n_] := Product[s[k] + t[n - k], {k, 0, n}]
    Table[Expand[u[n]], {n, 0, 10}]
    Column[Table[CoefficientList[Expand[u[n]], x], {n, 0, 10}]]   (* array *)
    Flatten[Table[CoefficientList[Expand[u[n]], x], {n, 0, 10}]]  (* sequence *)

A375042 Irregular triangular array T; row n shows the coefficients of the (n-1)-st polynomial in the obverse convolution s(x)**t(x), where s(x) = n^2 x and t(x) = 2x+1. See Comments.

Original entry on oeis.org

1, 2, 1, 5, 6, 1, 11, 36, 36, 1, 22, 157, 432, 396, 1, 40, 553, 3258, 8172, 7128, 1, 67, 1633, 18189, 96138, 227772, 192456, 1, 105, 4179, 80243, 787320, 3881016, 8847792, 7313328, 1, 156, 9534, 293372, 4879713, 44034336, 206779608, 458550720, 372979728, 1
Offset: 1

Views

Author

Clark Kimberling, Sep 11 2024

Keywords

Comments

See A374848 for the definition of obverse convolution and a guide to related sequences and arrays.

Examples

			First 3 polynomials in s(x)**t(x) are
  1 + 2x,
  1 + 5 x + 6 x^2,
  1 + 11 x + 36 x^2 + 36 x^3.
First 5 rows of array:
  1   2
  1   5      6
  1   11    36    36
  1   22   157   432   396
  1   40   553  3258  8172  7128
		

Crossrefs

Cf. A000290, A277355 ((1/2)T(n,n+1)), A374848, A375041, A375043.

Programs

  • Mathematica
    s[n_] := n^2  x; t[n_] := 1 + 2 x;
    u[n_] := Product[s[k] + t[n - k], {k, 0, n}]
    Table[Expand[u[n]], {n, 0, 10}]
    Column[Table[CoefficientList[Expand[u[n]], x], {n, 0, 10}]]   (* array *)
    Flatten[Table[CoefficientList[Expand[u[n]], x], {n, 0, 10}]]    (* sequence *)

A375043 Irregular triangular array T; row n shows the coefficients of the (n-1)-st polynomial in the obverse convolution s(x)**t(x), where s(x) = n^2 x and t(x) = x+2. See Comments.

Original entry on oeis.org

2, 1, 4, 6, 2, 8, 32, 34, 10, 16, 144, 388, 360, 100, 32, 560, 3224, 7316, 6320, 1700, 64, 1952, 21008, 98456, 202856, 167720, 44200, 128, 6272, 114240, 974208, 4048584, 7841112, 6294040, 1635400, 256, 18944, 542080, 7660416, 56807568, 218111424, 404643680
Offset: 1

Views

Author

Clark Kimberling, Sep 14 2024

Keywords

Comments

See A374848 for the definition of obverse convolution and a guide to related sequences and arrays.

Examples

			First 3 polynomials in s(x)**t(x) are
2 + x,
4 + 6 x + 2 x^2,
8 + 32 x + 34 x^2 + 10 x^3.
First 5 rows of array:
 2    1
 4    6     2
 8   32    34    10
16  144   388   360   100
32  560  3224  7316  6320  1700
		

Crossrefs

Cf. A000290, A101686 (T(n,n+1)), A374848, A375041, A375042.

Programs

  • Mathematica
    s[n_] := n^2  x; t[n_] := x + 2;
    u[n_] := Product[s[k] + t[n - k], {k, 0, n}]
    Table[Expand[u[n]], {n, 0, 10}]
    Column[Table[CoefficientList[Expand[u[n]], x], {n, 0, 10}]]   (* array *)
    Flatten[Table[CoefficientList[Expand[u[n]], x], {n, 0, 10}]]  (* sequence *)

A375047 Irregular triangular array T; row n shows the coefficients of the (n-1)-st polynomial in the obverse convolution s(x)**t(x), where s(x) = x+1 and t(x) = F(n) = n-th Fibonacci number. See Comments.

Original entry on oeis.org

1, 1, 2, 3, 1, 4, 8, 5, 1, 12, 28, 23, 8, 1, 48, 124, 120, 55, 12, 1, 288, 792, 844, 450, 127, 18, 1, 2592, 7416, 8388, 4894, 1593, 289, 27, 1, 36288, 106416, 124848, 76904, 27196, 5639, 667, 41, 1, 798336, 2377440, 2853072, 1816736, 675216, 151254, 20313
Offset: 1

Views

Author

Clark Kimberling, Sep 15 2024

Keywords

Comments

See A374848 for the definition of obverse convolution and a guide to related sequences and arrays.

Examples

			First 3 polynomials in s(x)**t(x) are
1 + x,
2 + 3 x + x^2,
4 + 8 x + 5 x^2 + x^3.
First 5 rows of array:
 1    1
 2    3    1
 4    8    5   1
12   28   23   8   1
48  124  120  55  12  1
		

Crossrefs

Programs

  • Mathematica
    s[n_] := x + 1; t[n_] := Fibonacci[n];
    u[n_] := Product[s[k] + t[n - k], {k, 0, n}]
    Table[Expand[u[n]], {n, 0, 10}]
    Column[Table[CoefficientList[Expand[u[n]], x], {n, 0, 10}]]   (* array *)
    Flatten[Table[CoefficientList[Expand[u[n]], x], {n, 0, 10}]]  (* sequence *)

A375048 Irregular triangular array T; row n shows the coefficients of the (n-1)-st polynomial in the obverse convolution s(x)**t(x), where s(x) = x+F(n) and t(x) = F(n), where F(n) = n-th Fibonacci number (A000045). See Comments.

Original entry on oeis.org

0, 1, 1, 2, 1, 2, 5, 4, 1, 16, 32, 24, 8, 1, 162, 297, 216, 78, 14, 1, 3600, 5640, 3649, 1248, 238, 24, 1, 147456, 196608, 110848, 34240, 6256, 676, 40, 1, 12320100, 13667940, 6521589, 1746426, 286843, 29568, 1867, 66, 1, 2058386904, 1878686460, 746158770
Offset: 1

Views

Author

Clark Kimberling, Sep 15 2024

Keywords

Comments

See A374848 for the definition of obverse convolution and a guide to related sequences and arrays.

Examples

			First 3 polynomials in s(x)**t(x) are
0 + x,
1 + 2 x + x^2,
2 + 4 x + 4 x^2 + x^3.
First 5 rows of array:
  0    1
  1    2    1
  2    5    4   1
 16   32   24   8   1
162  297  216  78  14  1
		

Crossrefs

Programs

  • Mathematica
    s[n_] := x + Fibonacci[n]; t[n_] := Fibonacci[n];
    u[n_] := Product[s[k] + t[n - k], {k, 0, n}]
    Table[Expand[u[n]], {n, 0, 10}]
    Column[Table[CoefficientList[Expand[u[n]], x], {n, 0, 10}]]   (* array *)
    Flatten[Table[CoefficientList[Expand[u[n]], x], {n, 0, 10}]]  (* sequence *)

A375049 Irregular triangular array T; row n shows the coefficients of the (n-1)-st polynomial in the obverse convolution s(x)**t(x), where s(x) = x+F(n) and t(x) = x+F(n), and F(n) = n-th Fibonacci number (A000045). See Comments.

Original entry on oeis.org

0, 2, 1, 4, 4, 2, 10, 16, 8, 16, 64, 96, 64, 16, 162, 594, 864, 624, 224, 32, 3600, 11280, 14596, 9984, 3808, 768, 64, 147456, 393216, 443392, 273920, 100096, 21632, 2560, 128, 12320100, 27335880, 26086356, 13971408, 4589488, 946176, 119488, 8448, 256
Offset: 1

Views

Author

Clark Kimberling, Jul 31 2024

Keywords

Comments

See A374848 for the definition of obverse convolution and a guide to related sequences and arrays. If n is odd, then the polynomial u(n) is a square. Every T(n,k) except T(2,1) is even.

Examples

			First 3 polynomials in s(x)**t(x) are
  0 + 2x,
  1 + 4 x + 4x^2,
  2 + 10 x + 16 x^2 + 8 x^3.
First 5 rows of array:
  0   2
  1   4   4
  2   10  16   8
  16  64  96  64  16
  162 594 864 624 224 32
		

Crossrefs

Cf. A000045, A000079 (T(n,n+1)), A374848, A375047, A375048.

Programs

  • Mathematica
    s[n_] := x + Fibonacci[n]; t[n_] := Fibonacci[n];
    u[n_] := Product[s[k] + t[n - k], {k, 0, n}]
    Table[Expand[u[n]], {n, 0, 10}]
    Column[Table[CoefficientList[Expand[u[n]], x], {n, 0, 10}]]   (* array *)
    Flatten[Table[CoefficientList[Expand[u[n]], x], {n, 0, 10}]]    (* sequence *)

A374877 Obverse convolution (3n+1)**(3n+1); see Comments.

Original entry on oeis.org

2, 25, 512, 14641, 537824, 24137569, 1280000000, 78310985281, 5429503678976, 420707233300201, 36028797018963968, 3379220508056640625, 344498040522809827328, 37929227194915558802161, 4485286068729022118887424, 566977372488557307219621121
Offset: 0

Views

Author

Clark Kimberling, Sep 13 2024

Keywords

Comments

See A374848 for the definition of obverse convolution and a guide to related sequences.
If k>=0, then a(2k) is even and a(2k+1) is a square.

Crossrefs

Programs

  • Mathematica
    s[n_] := 3 n + 1; t[n_] := 3 n + 1;
    u[n_] := Product[s[k] + t[n - k], {k, 0, n}]
    Table[u[n], {n, 0, 17}]
    (* or *)
    Table[(3*n+2)^(n+1), {n,0,20}] (* Vaclav Kotesovec, Sep 13 2024 *)

Formula

From Vaclav Kotesovec, Sep 13 2024: (Start)
a(n) = (3*n+2)^(n+1).
a(n) ~ exp(2/3) * 3^(n+1) * n^(n+1). (End)
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