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.

Previous Showing 21-28 of 28 results.

A325537 Irregular triangle whose rows are the sorted combined parts of all strict integer partitions of n.

Original entry on oeis.org

1, 2, 1, 2, 3, 1, 3, 4, 1, 2, 3, 4, 5, 1, 1, 2, 2, 3, 4, 5, 6, 1, 1, 2, 2, 3, 4, 4, 5, 6, 7, 1, 1, 1, 2, 2, 3, 3, 4, 5, 5, 6, 7, 8, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 5, 5, 6, 6, 7, 8, 9, 1, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 5, 5, 6, 6, 7, 7, 8, 9, 10
Offset: 1

Views

Author

Gus Wiseman, May 08 2019

Keywords

Examples

			The strict integer partitions of 6 are {(6), (5,1), (4,2), (3,2,1)} with multiset union {1,1,2,2,3,4,5,6}, which is row n = 6.
Triangle begins:
  1
  2
  1 2 3
  1 3 4
  1 2 3 4 5
  1 1 2 2 3 4 5 6
  1 1 2 2 3 4 4 5 6 7
  1 1 1 2 2 3 3 4 5 5 6 7 8
  1 1 1 2 2 2 3 3 3 4 4 5 5 6 6 7 8 9
		

Crossrefs

Row lengths are A015723.
Row sums are A066189.
Row products are A325504.
Run-lengths of row n are row n of A325513.

Programs

  • Mathematica
    Table[Sort[Join@@Select[IntegerPartitions[n],UnsameQ@@#&]],{n,10}]

A347060 Total number of 1's in the binary expansion of parts in all partitions of n into distinct parts.

Original entry on oeis.org

0, 1, 1, 4, 4, 7, 11, 15, 20, 28, 39, 48, 64, 80, 104, 134, 167, 203, 257, 311, 381, 470, 566, 680, 820, 981, 1168, 1394, 1650, 1946, 2300, 2700, 3161, 3705, 4315, 5026, 5845, 6769, 7827, 9049, 10424, 11992, 13784, 15801, 18088, 20702, 23620, 26922, 30665
Offset: 0

Views

Author

Alois P. Heinz, Aug 14 2021

Keywords

Examples

			a(5) = 7 counts the 1's in [101], [100, 1], [11, 10].
		

Crossrefs

Programs

  • Maple
    h:= proc(n) option remember; add(i, i=Bits[Split](n)) end:
    b:= proc(n, i) option remember; `if`(n=0, [1, 0],
          `if`(n>i*(i+1)/2, 0, b(n, i-1)+(p-> p+
           [0, p[1]*h(i)])(b(n-i, min(n-i, i-1)))))
        end:
    a:= n-> b(n$2)[2]:
    seq(a(n), n=0..60);

A278406 G.f.: x^2 * f''(x), where f(x) = Product_{k>=1} 1 / (1 - x^k).

Original entry on oeis.org

0, 0, 4, 18, 60, 140, 330, 630, 1232, 2160, 3780, 6160, 10164, 15756, 24570, 36960, 55440, 80784, 117810, 167580, 238260, 332640, 462924, 635030, 869400, 1174800, 1583400, 2113020, 2810808, 3706780, 4875480, 6363060, 8282208, 10711008, 13811820, 17710770
Offset: 0

Views

Author

Vaclav Kotesovec, Nov 21 2016

Keywords

Crossrefs

Programs

  • Mathematica
    nmax=60; CoefficientList[Series[x^2*D[Product[1/(1-x^k), {k, 1, nmax}], {x, 2}], {x, 0, nmax}], x]
    nmax=60; CoefficientList[Series[Product[1/(1-x^k), {k, 1, nmax}], {x, 0, nmax}], x]*Range[0, nmax]*(Range[0, nmax]-1)

Formula

a(n) = n*(n-1)*A000041(n).

A278407 G.f.: x^2 * f''(x), where f(x) = Product_{k>=1} (1 + x^k).

Original entry on oeis.org

0, 0, 2, 12, 24, 60, 120, 210, 336, 576, 900, 1320, 1980, 2808, 4004, 5670, 7680, 10336, 14076, 18468, 24320, 31920, 41118, 52624, 67344, 85200, 107250, 134784, 167832, 207872, 257520, 316200, 386880, 473088, 574464, 696150, 841680, 1012320, 1214784, 1455324
Offset: 0

Views

Author

Vaclav Kotesovec, Nov 21 2016

Keywords

Crossrefs

Programs

  • Maple
    g:= mul(1+x^k,k=1..100):
    S1:= series(g,x,101):
    S2:= series(x^2*diff(S1,x$2),x,101):
    seq(coeff(S2,x,j),j=0..100); # Robert Israel, Nov 22 2016
  • Mathematica
    nmax=60; CoefficientList[Series[x^2*D[Product[1+x^k, {k, 1, nmax}], {x, 2}], {x, 0, nmax}], x]
    nmax=60; CoefficientList[Series[Product[1+x^k, {k, 1, nmax}], {x, 0, nmax}], x]*Range[0, nmax]*(Range[0, nmax]-1)

Formula

a(n) = n*(n-1)*A000009(n).

A306918 Sum over all partitions of n into distinct parts of the power tower evaluation x^y^...^z, where x, y, ..., z are the parts in decreasing order.

Original entry on oeis.org

1, 1, 2, 5, 7, 18, 36, 118, 265, 263212, 2217881, 152599933940, 542101086242752217003726400434973829461152534, 63340828764059520458379290673240751904836319648345
Offset: 0

Views

Author

Alois P. Heinz, Mar 16 2019

Keywords

Comments

a(14) = 620606987...270037949 has 183231 decimal digits.

Examples

			a(0) = 1 because the empty partition () has no parts, the exponentiation operator ^ is right-associative, and 1 is the right identity of exponentiation.
a(6) = 3^2^1 + 4^2 + 5^1 + 6 = 9 + 16 + 5 + 6 = 36.
		

Crossrefs

Programs

  • Maple
    d:= proc(l) local i; for i to nops(l)-1 do
           if l[i]=l[i+1] then return fi od; l
        end:
    f:= l-> `if`(l=[], 1, l[1]^f(subsop(1=(), l))):
    a:= n-> add(f(l), l=map(l->d(sort(l, `>`)), combinat[partition](n))):
    seq(a(n), n=0..13);
  • Mathematica
    d[l_] := Module[{i}, For[i = 1, i <= Length[l] - 1, i++, If[l[[i]] == l[[i + 1]], Return[]]]; l];
    f[l_] := If[l == {}, 1, l[[1]]^f[Delete[l, 1]]];
    a[n_] := Sum[f[l], {l, ReverseSort /@ Select[IntegerPartitions[n], Length@# == Length@ Union@# &]}];
    a /@ Range[0, 13] (* Jean-François Alcover, May 04 2020, after Maple *)

A270105 a(n) = Sum_{k=0..n} k*A000009(k).

Original entry on oeis.org

0, 1, 3, 9, 17, 32, 56, 91, 139, 211, 311, 443, 623, 857, 1165, 1570, 2082, 2728, 3556, 4582, 5862, 7458, 9416, 11808, 14736, 18286, 22576, 27760, 33976, 41400, 50280, 60820, 73300, 88084, 105492, 125967, 150015, 178135, 210967, 249265, 293785, 345445, 405337
Offset: 0

Views

Author

Vaclav Kotesovec, Mar 12 2016

Keywords

Crossrefs

Partial sums of A066189.

Programs

  • Mathematica
    Table[Sum[PartitionsQ[k]*k, {k, 0, n}], {n, 0, 50}]

Formula

a(n) ~ 3^(1/4) * n^(3/4) * exp(sqrt(n/3)*Pi) / (2*Pi).
G.f.: x*f'(x)/(1 - x), where f(x) = Product_{k>=1} (1 + x^k). - Ilya Gutkovskiy, Apr 13 2017

A279412 Expansion of Sum_{k>=1} prime(k)*x^prime(k)/(1 + x^prime(k)) * Product_{k>=1} (1 + x^prime(k)).

Original entry on oeis.org

0, 2, 3, 0, 10, 0, 14, 8, 9, 20, 11, 24, 26, 28, 30, 48, 34, 72, 57, 80, 84, 88, 115, 120, 125, 156, 135, 168, 203, 180, 279, 224, 297, 306, 315, 396, 407, 418, 507, 480, 574, 630, 645, 748, 720, 828, 893, 960, 1029, 1150, 1122, 1300, 1378, 1458, 1650, 1624, 1824, 1856, 2065, 2220, 2379, 2480, 2646, 2816, 2925
Offset: 1

Views

Author

Ilya Gutkovskiy, Apr 11 2017

Keywords

Comments

Sum of all parts of all partitions of n into distinct primes.

Examples

			a(12) = 24 because we have [7, 5], [7, 3, 2] and 2*12 = 24.
		

Crossrefs

Programs

  • Mathematica
    nmax = 65; Rest[CoefficientList[Series[Sum[Prime[k] x^Prime[k]/(1 + x^Prime[k]), {k, 1, nmax}] Product[1 + x^Prime[k], {k, 1, nmax}], {x, 0, nmax}], x]]
    nmax = 65; Rest[CoefficientList[Series[x D[Product[1 + x^Prime[k], {k, 1, nmax}], x], {x, 0, nmax}], x]]

Formula

G.f.: Sum_{k>=1} prime(k)*x^prime(k)/(1 + x^prime(k)) * Product_{k>=1} (1 + x^prime(k)).
G.f.: x*f'(x), where f(x) = Product_{k>=1} (1 + x^prime(k)).
a(n) = n*A000586(n).

A304907 Expansion of x * (d/dx) 1/(1 - Sum_{k>=1} x^k/(1 + x^k)).

Original entry on oeis.org

0, 1, 2, 9, 16, 35, 84, 161, 312, 639, 1240, 2354, 4536, 8593, 16128, 30360, 56672, 105213, 195174, 360582, 664040, 1220730, 2238324, 4095035, 7479552, 13636750, 24821108, 45114813, 81887008, 148438211, 268763160, 486082263, 878200416, 1585098372, 2858378368, 5149986275
Offset: 0

Views

Author

Ilya Gutkovskiy, May 20 2018

Keywords

Comments

Sum of all parts of all Carlitz compositions (compositions without adjacent equal parts) of n.

Crossrefs

Programs

  • Mathematica
    nmax = 35; CoefficientList[Series[x D[1/(1 - Sum[x^k/(1 + x^k), {k, 1, nmax}]), x], {x, 0, nmax}], x]
    a[n_] := a[n] = If[n == 0, 1, Sum[Sum[-(-1)^d, {d, Divisors[k]}] a[n - k], {k, 1, n}]]; Table[n a[n], {n, 0, 35}]

Formula

a(n) = n*A003242(n).
Previous Showing 21-28 of 28 results.