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.
%I A064410 #41 Feb 12 2025 09:31:23
%S A064410 0,0,1,1,1,1,1,2,2,4,4,7,7,11,12,17,19,27,30,41,48,62,73,95,110,140,
%T A064410 166,206,243,302,354,435,513,622,733,887,1039,1249,1467,1750,2049,
%U A064410 2438,2847,3371,3934,4634,5398,6343,7367,8626,10009,11677,13521,15737,18184
%N A064410 Number of partitions of n with zero crank.
%C A064410 For a partition p, let l(p) = largest part of p, w(p) = number of 1's in p, m(p) = number of parts of p larger than w(p). The crank of p is given by l(p) if w(p) = 0, otherwise m(p)-w(p).
%H A064410 Alois P. Heinz and Vaclav Kotesovec, <a href="/A064410/b064410.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from Alois P. Heinz)
%H A064410 Brian Hopkins and James A. Sellers, <a href="https://arxiv.org/abs/2305.05096">On Blecher and Knopfmacher's Fixed Points for Integer Partitions</a>, arXiv:2305.05096 [math.CO], 2023. Mentions this sequence.
%H A064410 Brian Hopkins, James A. Sellers, and Dennis Stanton, <a href="https://arxiv.org/abs/2009.10873">Dyson's Crank and the Mex of Integer Partitions</a>, arXiv:2009.10873 [math.CO], 2020. Mentions this sequence.
%F A064410 a(n) = A000041(n) - 2*A001522(n). a(n) = A064391(n, 0).
%F A064410 a(n) ~ exp(Pi*sqrt(2*n/3)) * Pi / (3 * 2^(9/2) * n^(3/2)). - _Vaclav Kotesovec_, May 06 2018
%F A064410 a(n > 1) = A064428(n) - A001522(n), where A001522/A064428 count odd/even-length compositions with alternating parts strictly decreasing. - _Gus Wiseman_, Apr 02 2021
%F A064410 From _Peter Bala_, Feb 03 2024: (Start)
%F A064410 For n >= 2, a(n) = A188674(n+1) - A188674(n) (Hopkins and Sellers, Proposition 7).
%F A064410 Equivalently, the g.f. A(x) = (1 - x) * Sum_{n >= 1} x^(n*(n+2)) / Product{k = 1..n} (1 - x^k)^2. (End)
%e A064410 a(10)=4 because there are 4 partitions of 10 with zero crank: 1+1+2+3+3, 1+1+4+4, 1+1+3+5 and 1+9.
%e A064410 From _Gus Wiseman_, Apr 02 2021: (Start)
%e A064410 The a(3) = 1 through a(14) = 11 partitions (A..D = 10..13):
%e A064410 21 31 41 51 61 71 81 91 A1 B1 C1 D1
%e A064410 3311 4311 4411 5411 5511 6511 6611
%e A064410 5311 6311 6411 7411 7511
%e A064410 33211 43211 7311 8311 8411
%e A064410 44211 54211 9311
%e A064410 53211 63211 55211
%e A064410 332211 432211 64211
%e A064410 73211
%e A064410 442211
%e A064410 532211
%e A064410 3322211
%e A064410 (End)
%t A064410 nmax = 60; Rest[CoefficientList[Series[x - 1 + Sum[(-1)^k*(x^(k*(k + 1)/2) - x^(k*(k - 1)/2)), {k, 1, nmax}] / Product[1 - x^k, {k, 1, nmax}], {x, 0, nmax}], x]] (* _Vaclav Kotesovec_, Sep 26 2016 *)
%t A064410 Flatten[{0, Table[PartitionsP[n] - 2*Sum[(-1)^(j+1)*PartitionsP[n - j*((j+1)/2)], {j, 1, Floor[(Sqrt[8*n + 1] - 1)/2]}], {n, 2, 60}]}] (* _Vaclav Kotesovec_, Sep 26 2016 *)
%t A064410 ck[y_]:=With[{w=Count[y,1]},If[w==0,Max@@y,Count[y,_?(#>w&)]-w]];
%t A064410 Table[Length[Select[IntegerPartitions[n],ck[#]==0&]],{n,0,30}] (* _Gus Wiseman_, Apr 02 2021 *)
%o A064410 (Sage)
%o A064410 [[p.crank() for p in Partitions(n)].count(0) for n in (1..20)] # _Peter Luschny_, Sep 15 2014
%Y A064410 The version for positive crank is A001522.
%Y A064410 Central column of A064391.
%Y A064410 The version for nonnegative crank is A064428.
%Y A064410 The Heinz numbers of these partitions are A342192.
%Y A064410 A003242 counts anti-run compositions.
%Y A064410 A224958 counts compositions with alternating parts unequal.
%Y A064410 A257989 gives the crank of the partition with Heinz number n.
%Y A064410 Cf. A000009, A000041, A000726, A027193, A034008, A062968, A114921, A188674, A342194, A342343, A342528.
%K A064410 nonn,easy
%O A064410 1,8
%A A064410 _Vladeta Jovovic_, Sep 29 2001
%E A064410 More terms from _Reiner Martin_, Dec 26 2001