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 10 results.

A300439 Number of odd enriched p-trees of weight n (all outdegrees are odd).

Original entry on oeis.org

1, 1, 2, 2, 5, 7, 18, 29, 75, 132, 332, 651, 1580, 3268, 7961, 16966, 40709, 89851, 215461, 484064, 1159568, 2641812, 6337448, 14622880, 35051341, 81609747, 196326305, 459909847, 1107083238, 2611592457, 6299122736, 14926657167, 36069213786, 85809507332
Offset: 1

Views

Author

Gus Wiseman, Mar 05 2018

Keywords

Comments

An odd enriched p-tree of weight n > 0 is either a single node of weight n, or a finite odd-length sequence of at least 3 odd enriched p-trees whose weights are weakly decreasing and sum to n.

Examples

			The a(6) = 7 odd enriched p-trees: 6, (411), (321), (222), ((111)21), ((211)11), (21111).
		

Crossrefs

Programs

  • Mathematica
    f[n_]:=f[n]=1+Sum[Times@@f/@y,{y,Select[IntegerPartitions[n],Length[#]>1&&OddQ[Length[#]]&]}];
    Array[f,40]
  • PARI
    seq(n)={my(v=vector(n)); for(n=1, n, v[n] = 1 + polcoef(1/prod(k=1, n-1, 1 - v[k]*x^k + O(x*x^n)) - 1/prod(k=1, n-1, 1 + v[k]*x^k + O(x*x^n)), n)/2); v} \\ Andrew Howroyd, Aug 26 2018

A300647 Number of same-trees of weight n in which all outdegrees are odd.

Original entry on oeis.org

1, 1, 2, 1, 2, 2, 2, 1, 10, 2, 2, 2, 2, 2, 42, 1, 2, 10, 2, 2, 138, 2, 2, 2, 34, 2, 1514, 2, 2, 42, 2, 1, 2058, 2, 162, 10, 2, 2, 8202, 2, 2, 138, 2, 2, 207370, 2, 2, 2, 130, 34, 131082, 2, 2, 1514, 2082, 2, 524298, 2, 2, 42, 2, 2, 14725738, 1, 8226, 2058, 2
Offset: 1

Views

Author

Gus Wiseman, Mar 10 2018

Keywords

Comments

A same-tree of weight n > 0 is either a single node of weight n, or a finite sequence of two or more same-trees whose weights are all equal and sum to n.

Examples

			The a(9) = 10 odd same-trees:
9,
(333),
(33(111)), (3(111)3), ((111)33)
(3(111)(111)), ((111)3(111)), ((111)(111)3),
((111)(111)(111)), (111111111).
		

Crossrefs

Programs

  • Mathematica
    a[n_]:=1+Sum[a[n/d]^d,{d,Select[Rest[Divisors[n]],OddQ]}];
    Array[a,80]
  • PARI
    a(n) = if (n==1, 1, 1+sumdiv(n, d, if ((d > 1) && (d % 2), a(n/d)^d))); \\ Michel Marcus, Mar 10 2018

Formula

a(n) = 1 + Sum_d a(n/d)^d where the sum is over odd divisors of n greater than 1.

A300862 Solution to 1 = Sum_y Product_{k in y} a(k) for each n > 0, where the sum is over all integer partitions of n with an odd number of parts.

Original entry on oeis.org

1, 1, 0, 0, -1, -1, 0, 1, 1, 0, -2, -3, -2, 2, 7, 6, -3, -15, -19, -2, 32, 54, 24, -64, -153, -123, 95, 389, 444, -43, -966, -1475, -516, 2066, 4414, 3092, -3874, -12480, -12936, 3847, 32445, 45494, 8950, -77282, -147663, -86313, 157456, 435623, 399041, -229616, -1211479, -1535700, -73132
Offset: 1

Views

Author

Gus Wiseman, Mar 13 2018

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_]:=a[n]=1-Sum[Times@@a/@y,{y,Select[IntegerPartitions[n],Length[#]>1&&OddQ[Length[#]]&]}];
    Array[a,40]

A300440 Number of odd strict trees of weight n (all outdegrees are odd).

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 2, 3, 5, 7, 11, 18, 27, 45, 75, 125, 207, 353, 591, 1013, 1731, 2984, 5122, 8905, 15369, 26839, 46732, 81850, 142932, 251693, 441062, 778730, 1370591, 2425823, 4281620, 7601359, 13447298, 23919512, 42444497, 75632126, 134454505, 240100289
Offset: 1

Views

Author

Gus Wiseman, Mar 05 2018

Keywords

Comments

An odd strict tree of weight n is either a single node of weight n, or a finite odd-length sequence of at least 3 odd strict trees with strictly decreasing weights summing to n.

Examples

			The a(10) = 7 odd strict trees: 10, (721), (631), (541), (532), ((421)21), ((321)31).
		

Crossrefs

Programs

  • Mathematica
    g[n_]:=g[n]=1+Sum[Times@@g/@y,{y,Select[IntegerPartitions[n],Length[#]>1&&OddQ[Length[#]]&&UnsameQ@@#&]}];
    Array[g,20]
  • PARI
    seq(n)={my(v=vector(n)); for(n=1, n, v[n] = 1 + polcoef(prod(k=1, n-1, 1 + v[k]*x^k + O(x*x^n)) - prod(k=1, n-1, 1 - v[k]*x^k + O(x*x^n)), n)/2); v} \\ Andrew Howroyd, Aug 25 2018

A300648 Number of orderless same-trees of weight n in which all outdegrees are odd.

Original entry on oeis.org

1, 1, 2, 1, 2, 2, 2, 1, 6, 2, 2, 2, 2, 2, 12, 1, 2, 6, 2, 2, 14, 2, 2, 2, 8, 2, 68, 2, 2, 12, 2, 1, 18, 2, 16, 6, 2, 2, 20, 2, 2, 14, 2, 2, 644, 2, 2, 2, 10, 8, 24, 2, 2, 68, 20, 2, 26, 2, 2, 12, 2, 2, 1386, 1, 22, 18, 2, 2, 30, 16, 2, 6, 2, 2, 4532, 2, 22, 20
Offset: 1

Views

Author

Gus Wiseman, Mar 10 2018

Keywords

Comments

An orderless same-tree of weight n > 0 is either a single node of weight n, or a finite multiset of two or more orderless same-trees whose weights are all equal and sum to n.

Examples

			The a(9) = 6 odd orderless same-trees: 9, (333), (33(111)), (3(111)(111)), ((111)(111)(111)), (111111111).
		

Crossrefs

Programs

  • Mathematica
    a[n_]:=1+Sum[Binomial[a[n/d]+d-1,d],{d,Select[Rest[Divisors[n]],OddQ]}];
    Array[a,80]
  • PARI
    a(n) = if (n==1, 1, 1 + sumdiv(n, d, if ((d > 1) && (d % 2), binomial(a(n/d) + d - 1, d)))); \\ Michel Marcus, Mar 10 2018

Formula

a(n) = 1 + Sum_d binomial(a(n/d) + d - 1, d) where the sum is over odd divisors of n greater than 1.

A300649 Number of same-trees of weight 2n + 1 in which all outdegrees are odd and all leaves greater than 1.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 3, 1, 1, 3, 1, 2, 10, 1, 1, 3, 3, 1, 3, 1, 1, 62, 1, 2, 3, 1, 3, 3, 1, 1, 158, 3, 1, 3, 1, 1, 254, 3, 1, 1514, 1, 3, 3, 1, 3, 3, 3, 1, 2078, 1, 1, 2461, 1, 1, 3, 1, 3, 8222, 3, 2, 3, 34, 1, 3, 1, 3, 390782, 1, 1, 3, 3, 3, 2198, 1, 1
Offset: 0

Views

Author

Gus Wiseman, Mar 10 2018

Keywords

Comments

A same-tree of weight n > 0 is either a single node of weight n, or a finite sequence of two or more same-trees whose weights are all equal and sum to n.

Examples

			The a(13) = 10 odd same-trees with all leaves greater than 1:
27,
(999),
(99(333)), (9(333)9), ((333)99),
(9(333)(333)), ((333)9(333)), ((333)(333)9),
((333)(333)(333)), (333333333).
		

Crossrefs

Programs

  • Mathematica
    a[n_]:=If[n===1,1,Sum[a[n/d]^d,{d,Select[Rest[Divisors[n]],OddQ]}]];
    Table[a[n],{n,1,100,2}]
  • PARI
    f(n) = if (n==1, 1, sumdiv(n, d, if ((d > 1) && (d % 2), f(n/d)^d)));
    a(n) = f(2*n+1); \\ Michel Marcus, Mar 10 2018

Formula

a(1) = 1; a(n > 1) = Sum_d a(n/d)^d where the sum is over odd divisors of n greater than 1.

A300650 Number of orderless same-trees of weight 2n + 1 in which all outdegrees are odd and all leaves greater than 1.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 3, 1, 1, 3, 1, 2, 6, 1, 1, 3, 3, 1, 3, 1, 1, 19, 1, 2, 3, 1, 3, 3, 1, 1, 21, 3, 1, 3, 1, 1, 28, 3, 1, 68, 1, 3, 3, 1, 3, 3, 3, 1, 25, 1, 1, 71, 1, 1, 3, 1, 3, 27, 3, 2, 3, 8, 1, 3, 1, 3, 1656, 1, 1, 3, 3, 3, 43, 1, 1, 31, 3, 1, 3, 3, 1
Offset: 0

Views

Author

Gus Wiseman, Mar 10 2018

Keywords

Comments

An orderless same-tree of weight n > 0 is either a single node of weight n, or a finite multiset of two or more orderless same-trees whose weights are all equal and sum to n.

Examples

			The a(13) = 6 orderless same-trees: 27, (999), (99(333)), (9(333)(333)), ((333)(333)(333)), (333333333).
		

Crossrefs

Programs

  • Mathematica
    a[n_]:=If[n===1,1,Sum[Binomial[a[n/d]+d-1,d],{d,Select[Rest[Divisors[n]],OddQ]}]];
    Table[a[n],{n,1,100,2}]
  • PARI
    f(n) = if (n==1, 1, sumdiv(n, d, if ((d > 1) && (d % 2), binomial(f(n/d)+d-1, d))));
    a(n) = f(2*n+1); \\ Michel Marcus, Mar 10 2018

Formula

a(1) = 1; a(n > 1) = Sum_d binomial(a(n/d) + d - 1, d) where the sum is over odd divisors of n greater than 1.

A300652 Number of enriched p-trees of weight 2n + 1 in which all outdegrees and all leaves are odd.

Original entry on oeis.org

1, 2, 4, 12, 40, 136, 496, 1952, 7488, 30368, 123456, 512384, 2129664, 9068672, 38391552, 165642752, 713405952, 3109135872, 13528865792, 59591322624, 261549260800, 1159547047936, 5131968999424, 22883893137408, 101851069587456, 456703499042816, 2042949493276672
Offset: 0

Views

Author

Gus Wiseman, Mar 10 2018

Keywords

Comments

An enriched p-tree of weight n > 0 is either a single node of weight n, or a finite sequence of at least two enriched p-trees whose weights are weakly decreasing and sum to n.

Examples

			The a(3) = 12 trees:
7,
(511), (331),
((111)31), (3(111)1), ((311)11), (31111),
((111)(111)1), (((111)11)11), ((11111)11), ((111)1111), (1111111).
		

Crossrefs

Programs

  • Mathematica
    r[n_]:=r[n]=If[OddQ[n],1,0]+Sum[Times@@r/@y,{y,Select[IntegerPartitions[n],Length[#]>1&&OddQ[Length[#]]&]}];
    Table[r[n],{n,1,40,2}]
  • PARI
    seq(n)={my(v=vector(n)); for(n=1, n, v[n] = 1 + polcoef(1/prod(k=1, n-1, 1 - v[k]*x^(2*k-1) + O(x^(2*n))) - 1/prod(k=1, n-1, 1 + v[k]*x^(2*k-1) + O(x^(2*n))), 2*n-1)/2); v} \\ Andrew Howroyd, Aug 26 2018

Formula

a(n) = (1 - (-1)^n)/2 + Sum_y Product_{i in y} a(i) where the sum is over all non-singleton integer partitions of n with an odd number of parts.

A300797 Number of strict trees of weight 2n + 1 in which all outdegrees and all leaves are odd.

Original entry on oeis.org

1, 1, 1, 1, 2, 2, 4, 6, 11, 17, 34, 59, 118, 213, 424, 799, 1606, 3072, 6216, 12172, 24650, 48710, 99333, 198237, 405526, 815267, 1673127, 3387165, 6974702, 14179418, 29285048, 59841630, 123848399, 253927322, 526936694, 1084022437, 2253778793, 4649778115
Offset: 0

Views

Author

Gus Wiseman, Mar 13 2018

Keywords

Comments

A strict tree of weight n > 0 is either a single node of weight n, or a sequence of two or more strict trees with strictly decreasing weights summing to n.

Examples

			The a(7) = 6 strict trees: 15, (11 3 1), (9 5 1), (7 5 3), ((7 3 1) 3 1), ((5 3 1) 5 1).
		

Crossrefs

Programs

  • Mathematica
    a[n_]:=a[n]=If[OddQ[n],1,0]+Sum[Times@@a/@ptn,{ptn,Select[IntegerPartitions[n],Length[#]>1&&OddQ[Length[#]]&&UnsameQ@@#&]}];
    Table[a[n],{n,1,60,2}]
  • PARI
    seq(n)={my(v=vector(n)); for(n=1, n, v[n] = 1 + polcoef(prod(k=1, n-1, 1 + v[k]*x^(2*k-1) + O(x^(2*n))) - prod(k=1, n-1, 1 - v[k]*x^(2*k-1) + O(x^(2*n))), 2*n-1)/2); v} \\ Andrew Howroyd, Aug 26 2018

Extensions

a(30)-a(37) from Alois P. Heinz, Mar 13 2018

A318485 Number of p-trees of weight 2n + 1 in which all outdegrees are odd.

Original entry on oeis.org

1, 1, 2, 5, 13, 37, 107, 336, 1037, 3367, 10924, 36438, 121045, 412789, 1398168, 4831708, 16636297, 58084208, 202101971, 712709423, 2502000811, 8880033929, 31428410158, 112199775788, 399383181020, 1433385148187, 5128572792587, 18481258241133
Offset: 0

Views

Author

Gus Wiseman, Aug 27 2018

Keywords

Comments

A p-tree of weight n with odd outdegrees is either a single node (if n = 1) or a finite odd-length sequence of at least 3 p-trees with odd outdegrees whose weights are weakly decreasing and sum to n.

Examples

			The a(4) = 13 p-trees of weight 9 with odd outdegrees:
  ((((ooo)oo)oo)oo)
  (((ooo)(ooo)o)oo)
  (((ooo)oo)(ooo)o)
  ((ooo)(ooo)(ooo))
  (((ooooo)oo)oo)
  (((ooo)oooo)oo)
  ((ooooo)(ooo)o)
  (((ooo)oo)oooo)
  ((ooo)(ooo)ooo)
  ((ooooooo)oo)
  ((ooooo)oooo)
  ((ooo)oooooo)
  (ooooooooo)
		

Crossrefs

Programs

  • Mathematica
    b[n_]:=b[n]=If[n>1,0,1]+Sum[Times@@b/@y,{y,Select[IntegerPartitions[n],Length[#]>1&&OddQ[Length[#]]&]}];
    Table[b[n],{n,1,20,2}]
  • PARI
    seq(n)={my(v=vector(n)); v[1]=1; for(n=2, n, v[n] = polcoef(1/prod(k=1, n-1, 1 - v[k]*x^(2*k-1) + O(x^(2*n))) - 1/prod(k=1, n-1, 1 + v[k]*x^(2*k-1) + O(x^(2*n))), 2*n-1)/2); v} \\ Andrew Howroyd, Aug 27 2018
Showing 1-10 of 10 results.