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 1-3 of 3 results.

A281689 Expansion of Sum_{k>=2} x^Fibonacci(k)/(1 - x^Fibonacci(k)) / Product_{k>=2} (1 - x^Fibonacci(k)).

Original entry on oeis.org

1, 3, 6, 11, 18, 29, 42, 62, 86, 119, 159, 211, 273, 352, 446, 562, 697, 864, 1054, 1284, 1550, 1860, 2220, 2639, 3114, 3669, 4293, 5011, 5823, 6745, 7783, 8956, 10268, 11747, 13390, 15237, 17281, 19561, 22089, 24889, 27979, 31405, 35157, 39309, 43856, 48849, 54319, 60309, 66840, 73992, 81760, 90243
Offset: 1

Views

Author

Ilya Gutkovskiy, Jan 27 2017

Keywords

Comments

Total number of parts in all partitions of n into Fibonacci parts (with a single type of 1).
Convolution of A003107 and A005086.

Examples

			a(5) = 18 because we have [5], [3, 2], [3, 1, 1], [2, 2, 1], [2, 1, 1, 1], [1, 1, 1, 1, 1] and 1 + 2 + 3 + 3 + 4 + 5 = 18.
		

Crossrefs

Programs

  • Maple
    h:= proc(n) option remember; `if`(n<1, 0, `if`((t->
          issqr(t+4) or issqr(t-4))(5*n^2), n, h(n-1)))
        end:
    b:= proc(n, i) option remember; `if`(n=0 or i=1, [1, n],
           b(n, h(i-1))+(p->p+[0, p[1]])(b(n-i, h(min(n-i, i)))))
        end:
    a:= n-> b(n, h(n))[2]:
    seq(a(n), n=1..70);  # Alois P. Heinz, Sep 18 2018
  • Mathematica
    Rest[CoefficientList[Series[Sum[x^Fibonacci[k]/(1 - x^Fibonacci[k]), {k, 2, 20}]/Product[1 - x^Fibonacci[k], {k, 2, 20}], {x, 0, 52}], x]]

Formula

G.f.: Sum_{k>=2} x^Fibonacci(k)/(1 - x^Fibonacci(k)) / Product_{k>=2} (1 - x^Fibonacci(k)).
a(n) = Sum_{k=1..n} k * A319394(n,k). - Alois P. Heinz, Sep 18 2018

A240224 Irregular triangular array read by rows: row n gives a list of the partitions of n into distinct Fibonacci numbers. The order of the partitions is like in Abramowitz-Stegun.

Original entry on oeis.org

1, 2, 3, 2, 1, 3, 1, 5, 3, 2, 5, 1, 3, 2, 1, 5, 2, 8, 5, 3, 5, 2, 1, 8, 1, 5, 3, 1, 8, 2, 5, 3, 2, 8, 3, 8, 2, 1, 5, 3, 2, 1, 8, 3, 1, 13, 8, 5, 8, 3, 2, 13, 1, 8, 5, 1, 8, 3, 2, 1, 13, 2, 8, 5, 2, 13, 3, 13, 2, 1, 8, 5, 3, 8, 5, 2, 1, 13, 3, 1, 8, 5, 3, 1, 13, 5, 13, 3, 2, 8, 5, 3, 2, 13, 5, 1, 13, 3, 2, 1, 8, 5, 3, 2, 1, 13, 5, 2
Offset: 1

Views

Author

Wolfdieter Lang, Apr 07 2014

Keywords

Comments

The row length sequence is A240225. The number of partitions in row n is A000119(n).
The order of the partitions is like in Abramowitz-Stegun (rising number of parts, within like part numbers lexicographic) but here the order of the parts has been reversed, that is they are ordered decreasingly.

Examples

			The array with separated partitions begins:
n\k       1         2          3         4            5 ...
1:        1
2:        2
3:        3       2,1
4:      3,1
5:        5       3,2
6:      5,1     3,2,1
7:      5,2
8:        8       5,3      5,2,1
9:      8,1     5,3,1
10:     8,2     5,3,2
11:     8,3     8,2,1    5,3,2,1
12:   8,3,1
13:      13       8,5      8,3,2
14:    13,1     8,5,1    8,3,2,1
15:    13,2     8,5,2
16:    13,3    13,2,1      8,5,3   8,5,2,1
17:  13,3,1   8,5,3,1
18:    13,5    13,3,2    8,5,3,2
19:  13,5,1  13,3,2,1  8,5,3,2,1
20:  13,5,2
21:      21      13,8     13,5,3  13,5,2,1
22:    21,1    13,8,1   13,5,3,1
23:    21,2    13,8,2   13,5,3,2
24:    21,3    21,2,1     13,8,3  13,8,2,1   13,5,3,2,1
25:  21,3,1  13,8,3,1
...
		

Crossrefs

A290327 Total number of parts in all partitions of n into distinct Lucas numbers (beginning with 1) (A000204).

Original entry on oeis.org

1, 0, 1, 3, 2, 0, 3, 5, 0, 2, 6, 5, 0, 5, 9, 3, 0, 6, 9, 0, 5, 12, 7, 0, 9, 12, 0, 3, 10, 9, 0, 9, 17, 7, 0, 12, 16, 0, 7, 18, 12, 0, 12, 18, 4, 0, 10, 14, 0, 9, 21, 12, 0, 17, 22, 0, 7, 21, 16, 0, 16, 27, 9, 0, 18, 23, 0, 12, 27, 15, 0, 18, 22, 0, 4, 15, 14, 0, 14, 27, 12, 0, 21, 27, 0, 12, 32, 22, 0, 22
Offset: 1

Views

Author

Ilya Gutkovskiy, Jul 27 2017

Keywords

Examples

			a(8) = 5 because we have [7, 1], [4, 3, 1] and 2 + 3 = 5.
		

Crossrefs

Programs

  • Mathematica
    nmax = 90; Rest[CoefficientList[Series[Sum[x^LucasL[i]/(1 + x^LucasL[i]) Product[(1 + x^LucasL[j]), {j, 1, nmax}], {i, 1, nmax}], {x, 0, nmax}], x]]

Formula

G.f.: Sum_{i>=1} x^A000204(i)/(1 + x^A000204(i))*Product_{j>=1} (1 + x^A000204(j)).
Showing 1-3 of 3 results.