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.

A316938 Triangle read by rows formed using Pascal's rule except that n-th row begins and ends with Fibonacci(n+4).

Original entry on oeis.org

3, 5, 5, 8, 10, 8, 13, 18, 18, 13, 21, 31, 36, 31, 21, 34, 52, 67, 67, 52, 34, 55, 86, 119, 134, 119, 86, 55, 89, 141, 205, 253, 253, 205, 141, 89, 144, 230, 346, 458, 506, 458, 346, 230, 144, 233, 374, 576, 804, 964, 964, 804, 576, 374, 233, 377, 607, 950, 1380, 1768, 1928, 1768, 1380, 950, 607, 377
Offset: 0

Views

Author

Vincenzo Librandi, Jul 27 2018

Keywords

Comments

Row sums give A316937.

Examples

			Triangle begins:
    3;
    5,   5;
    8,  10,   8;
   13,  18,  18,  13;
   21,  31,  36,  31,  21;
   34,  52,  67,  67,  52,  34;
   55,  86, 119, 134, 119,  86,  55;
   89, 141, 205, 253, 253, 205, 141,  89;
  144, 230, 346, 458, 506, 458, 346, 230, 144;
...
		

Crossrefs

Cf. A000045 (Fibonacci numbers), A316937 (row sums).
Other Fibonacci borders: A074829, A108617, A316939.

Programs

  • Mathematica
    t={}; Do[r={}; Do[If[k==0||k==n, m=Fibonacci[n+4], m=t[[n,k]]+t[[n,k+1]]]; r=AppendTo[r, m], {k, 0, n}]; AppendTo[t, r], {n, 0, 10}]; t

A316528 a(n) = 3*a(n-1) - a(n-2) - 2*a(n-3) for n > 2, a(0)=1, a(1)=4, a(2)=10.

Original entry on oeis.org

1, 4, 10, 24, 54, 118, 252, 530, 1102, 2272, 4654, 9486, 19260, 38986, 78726, 158672, 319318, 641830, 1288828, 2586018, 5185566, 10393024, 20821470, 41700254, 83493244, 167136538, 334515862, 669424560, 1339484742, 2679997942, 5361659964, 10726012466, 21456381550
Offset: 0

Views

Author

Vincenzo Librandi, Jul 14 2018

Keywords

Comments

Row sums of triangle A316939.

Crossrefs

Programs

  • GAP
    a:=[1,4,10];; for n in [4..35] do a[n]:=3*a[n-1]-a[n-2]-2*a[n-3]; od; a; # Muniru A Asiru, Jul 14 2018
    
  • Magma
    I:=[1,4,10]; [n le 3 select I[n] else 3*Self(n-1)-Self(n-2)-2*Self(n-3): n in [1..40]];
    
  • Maple
    seq(coeff(series((1+x-x^2)/(1-3*x+x^2+2*x^3), x,n+1),x,n),n=0..35); # Muniru A Asiru, Jul 14 2018
  • Mathematica
    RecurrenceTable[{a[n] == 3 a[n - 1] - a[n - 2] - 2 a[n - 3], a[0] == 1, a[1] == 4, a[2] == 10}, a, {n, 0, 40}]
    Table[5 2^n - 2 Fibonacci[n + 3], {n, 0, 40}] (* Bruno Berselli, Jul 16 2018 *)
    LinearRecurrence[{3,-1,-2},{1,4,10},40] (* Harvey P. Dale, Jul 18 2020 *)
  • PARI
    Vec((1 + x - x^2)/((1 - 2*x)*(1 - x - x^2)) + O(x^40)) \\ Colin Barker, Jul 23 2018

Formula

G.f.: (1 + x - x^2)/((1 - 2*x)*(1 - x - x^2)).
a(n) = 2*A116712(n) for n > 0, a(0)=1.
a(n) = 5*2^n - 2*Fibonacci(n+3). - Bruno Berselli, Jul 16 2018
a(n) = (5*2^n - (2^(1-n)*((1-sqrt(5))^n*(-2+sqrt(5)) + (1+sqrt(5))^n*(2+sqrt(5))))/sqrt(5)). - Colin Barker, Jul 23 2018

A347584 Triangle formed by Pascal's rule, except that the n-th row begins and ends with the n-th Lucas number.

Original entry on oeis.org

2, 1, 1, 3, 2, 3, 4, 5, 5, 4, 7, 9, 10, 9, 7, 11, 16, 19, 19, 16, 11, 18, 27, 35, 38, 35, 27, 18, 29, 45, 62, 73, 73, 62, 45, 29, 47, 74, 107, 135, 146, 135, 107, 74, 47, 76, 121, 181, 242, 281, 281, 242, 181, 121, 76, 123, 197, 302, 423, 523, 562, 523, 423, 302, 197, 123
Offset: 0

Views

Author

Noah Carey and Greg Dresden, Sep 07 2021

Keywords

Comments

Similar in spirit to the Fibonacci-Pascal triangle A074829, which uses Fibonacci numbers instead of Lucas numbers at the ends of each row.
If we consider the top of the triangle to be the 0th row, then the sum of terms in n-th row is 2*(2^(n+1) - Lucas(n+1)). This sum also equals 2*A027973(n-1) for n>0.

Examples

			The first two Lucas numbers (for n=0 and n=1) are 2 and 1, so the first two rows (again, for n=0 and n=1) of the triangle are 2 and 1, 1 respectively.
Triangle begins:
               2;
             1,  1;
           3,  2,  3;
         4,  5,  5,  4;
       7,  9, 10,  9,  7;
    11, 16, 19, 19, 16, 11;
  18, 27, 35, 38, 35, 27, 18;
		

Crossrefs

Cf. A227550, A228196 (general formula).
Fibonacci borders: A074829, A108617, A316938, A316939.

Programs

  • Mathematica
    T[n_, 0] := LucasL[n]; T[n_, n_] := LucasL[n];
    T[n_, k_] := T[n - 1, k - 1] + T[n - 1, k];
    Table[T[n, k], {n, 0, 10}, {k, 0, n}] // Flatten

Formula

a(n) = 2*A074829(n+1) - A108617(n).

A379837 Triangle read by rows formed using Pascal's rule except that n-th row begins and ends with Fibonacci(n+3).

Original entry on oeis.org

2, 3, 3, 5, 6, 5, 8, 11, 11, 8, 13, 19, 22, 19, 13, 21, 32, 41, 41, 32, 21, 34, 53, 73, 82, 73, 53, 34, 55, 87, 126, 155, 155, 126, 87, 55, 89, 142, 213, 281, 310, 281, 213, 142, 89, 144, 231, 355, 494, 591, 591, 494, 355, 231, 144
Offset: 0

Views

Author

Vincenzo Librandi, Jan 26 2025

Keywords

Examples

			Triangle begins:
      k= 0   1   2  3    4   5   6
  n=0:   2;
  n=1:   3,  3;
  n=2:   5,  6,  5;
  n=3:   8, 11, 11, 8;
  n=4:  13, 19, 22, 19, 13;
  n=5:  21, 32, 41, 41, 32, 21;
  n=6:  34, 53, 73, 82, 73, 53, 34;
  ...
		

Crossrefs

Programs

  • Mathematica
    // As triangle // t={};Do[r={};Do[If[k==0||k==n,m=Fibonacci[n+3],m=t[[n,k]]+t[[n,k+1]]];r=AppendTo[r,m],{k,0,n}];AppendTo[t,r],{n,0,11}];t
Showing 1-4 of 4 results.