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.

A378716 Triangle read by rows: T(n,k) is the number of k-Fibonacci polyominoes with an area of n, with k > 1.

Original entry on oeis.org

1, 1, 1, 1, 0, 1, 2, 1, 0, 1, 2, 2, 0, 0, 1, 3, 0, 1, 0, 0, 1, 4, 2, 1, 0, 0, 0, 1, 5, 3, 1, 1, 0, 0, 0, 1, 7, 1, 1, 1, 0, 0, 0, 0, 1, 9, 5, 2, 0, 1, 0, 0, 0, 0, 1, 12, 5, 1, 1, 1, 0, 0, 0, 0, 0, 1, 16, 3, 2, 0, 0, 1, 0, 0, 0, 0, 0, 1, 21, 10, 3, 3, 0, 1, 0, 0, 0, 0, 0, 0, 1
Offset: 3

Views

Author

Stefano Spezia, Dec 05 2024

Keywords

Examples

			The triangle begins as:
   1;
   1, 1;
   1, 0, 1;
   2, 1, 0, 1;
   2, 2, 0, 0, 1;
   3, 0, 1, 0, 0, 1;
   4, 2, 1, 0, 0, 0, 1;
   5, 3, 1, 1, 0, 0, 0, 1;
   7, 1, 1, 1, 0, 0, 0, 0, 1;
   9, 5, 2, 0, 1, 0, 0, 0, 0, 1;
  12, 5, 1, 1, 1, 0, 0, 0, 0, 0, 1;
  ...
		

Crossrefs

Cf. A079957 (k=3), A182097 (k=2), A378704, A378706, A378707.

Programs

  • Mathematica
    T[n_, k_]:=SeriesCoefficient[1/(1-Sum[x^((k+i)(k-i+1)/2), {i, k}]), {x, 0, n}]; Table[T[n, k], {n, 2, 14}, {k, 2,n}]//Flatten

Formula

T(n, k) = [x^n] 1/(1 - Sum_{i=1..k} x^((k+i)*(k-i+1)/2) ).

A245367 Compositions of n into parts 3, 5 and 7.

Original entry on oeis.org

1, 0, 0, 1, 0, 1, 1, 1, 2, 1, 3, 3, 3, 6, 5, 8, 10, 11, 17, 18, 25, 32, 37, 52, 61, 79, 102, 123, 163, 200, 254, 326, 402, 519, 649, 819, 1045, 1305, 1664, 2096, 2643, 3358, 4220, 5352, 6759, 8527, 10806, 13622, 17237, 21785, 27501, 34802, 43934, 55544, 70209, 88672, 112131, 141644, 179018, 226274, 285860, 361358
Offset: 0

Views

Author

David Neil McGrath, Aug 20 2014

Keywords

Examples

			a(16) = 10: the compositions are the permutations of [5533] (there are 4!/2!2!=6 of them) and the permutations of [7333] (there are 4!/3!=4).
		

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{0,0,1,0,1,0,1},{1,0,0,1,0,1,1},70] (* Harvey P. Dale, Jan 27 2017 *)
  • PARI
    Vec(1/(1-x^3-x^5-x^7) +O(x^66)) \\ Joerg Arndt, Aug 20 2014

Formula

G.f: 1/(1-x^3-x^5-x^7).
a(n) = a(n-3) + a(n-5) + a(n-7).

A245369 Number of compositions of n into parts 3, 5 and 8.

Original entry on oeis.org

1, 0, 0, 1, 0, 1, 1, 0, 3, 1, 1, 5, 1, 5, 7, 2, 13, 9, 8, 25, 12, 26, 41, 22, 64, 62, 56, 130, 96, 146, 233, 174, 340, 391, 376, 703, 661, 862, 1327, 1211, 1905, 2379, 2449, 3935, 4251, 5216, 7641, 7911, 11056, 14271, 15576, 22632, 26433, 31848, 44544, 49920, 65536, 85248, 97344, 132712, 161601, 194728, 262504, 308865
Offset: 0

Views

Author

David Neil McGrath, Aug 23 2014

Keywords

Examples

			a(19)=25. The compositions of 19 into parts 3, 5, and 8 are the permutations of (883) (these are 3!/2!=3), (8533) (these are 4!/2!=12), and (55333) (these are 5!/3!2!=10).
		

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{0,0,1,0,1,0,0,1},{1,0,0,1,0,1,1,0},70] (* Harvey P. Dale, Sep 05 2022 *)
  • PARI
    Vec( 1/(1-x^3-x^5-x^8) +O(x^66) ) \\ Joerg Arndt, Aug 25 2014

Formula

G.f.: 1/(1-x^3-x^5-x^8).
a(n) = a(n-3) + a(n-5) + a(n-8).

A245370 Number of compositions of n into parts 3, 5 and 9.

Original entry on oeis.org

1, 0, 0, 1, 0, 1, 1, 0, 2, 2, 1, 3, 3, 3, 6, 5, 6, 11, 10, 13, 19, 19, 27, 35, 37, 52, 65, 74, 100, 121, 145, 192, 230, 282, 365, 440, 548, 695, 843, 1058, 1327, 1621, 2035, 2535, 3119, 3910, 4851, 5997, 7503, 9297, 11528, 14389, 17829, 22150, 27596, 34208, 42536, 52928, 65655, 81660, 101525, 126020, 156738, 194776, 241888
Offset: 0

Views

Author

David Neil McGrath, Aug 24 2014

Keywords

Examples

			a(28)=100 The compositions of n into parts 3,5 and 9 are the permutations of (9955)(these are 4!/2!2!=6), (555553) (these are 6!/5!=6), (955333) (these are 6!/3!2!=60), (55333333) (these are 8!/6!2!=28).
		

Crossrefs

Programs

  • PARI
    Vec( 1/(1-x^3-x^5-x^9) +O(x^66) ) \\ Joerg Arndt, Aug 24 2014

Formula

G.f.: 1/(1-x^3-x^5-x^9).
a(n) = a(n-3) + a(n-5) + a(n-9).
Showing 1-4 of 4 results.