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.

A344652 Number of permutations of the prime indices of n with no adjacent triples (..., x, y, z, ...) such that x <= y <= z.

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%I A344652 #7 Jun 18 2021 01:15:32
%S A344652 1,1,1,1,1,2,1,0,1,2,1,2,1,2,2,0,1,2,1,2,2,2,1,1,1,2,0,2,1,5,1,0,2,2,
%T A344652 2,3,1,2,2,1,1,5,1,2,2,2,1,0,1,2,2,2,1,1,2,1,2,2,1,7,1,2,2,0,2,5,1,2,
%U A344652 2,5,1,2,1,2,2,2,2,5,1,0,0,2,1,7,2,2,2
%N A344652 Number of permutations of the prime indices of n with no adjacent triples (..., x, y, z, ...) such that x <= y <= z.
%C A344652 A prime index of n is a number m such that prime(m) divides n. The multiset of prime indices of n is row n of A112798.
%e A344652 The permutations for n = 2, 6, 8, 30, 36, 60, 180, 210, 360:
%e A344652   (1)  (12)  (132)  (1212)  (1213)  (12132)  (1324)  (121213)
%e A344652        (21)  (213)  (2121)  (1312)  (13212)  (1423)  (121312)
%e A344652              (231)  (2211)  (1321)  (13221)  (1432)  (121321)
%e A344652              (312)          (2131)  (21213)  (2143)  (131212)
%e A344652              (321)          (2311)  (21312)  (2314)  (132121)
%e A344652                             (3121)  (21321)  (2413)  (132211)
%e A344652                             (3211)  (22131)  (2431)  (212131)
%e A344652                                     (23121)  (3142)  (213121)
%e A344652                                     (23211)  (3214)  (213211)
%e A344652                                     (31212)  (3241)  (221311)
%e A344652                                     (32121)  (3412)  (231211)
%e A344652                                     (32211)  (3421)  (312121)
%e A344652                                              (4132)  (321211)
%e A344652                                              (4213)
%e A344652                                              (4231)
%e A344652                                              (4312)
%e A344652                                              (4321)
%t A344652 Table[Length[Select[Permutations[Flatten[ ConstantArray@@@FactorInteger[n]]],!MatchQ[#,{___,x_,y_,z_,___}/;x<=y<=z]&]],{n,100}]
%Y A344652 All permutations of prime indices are counted by A008480.
%Y A344652 The case of permutations is A049774.
%Y A344652 Avoiding (3,2,1) also gives A344606.
%Y A344652 The wiggly case is A345164.
%Y A344652 A001250 counts wiggly permutations.
%Y A344652 A025047 counts wiggly compositions (ascend: A025048, descend: A025049).
%Y A344652 A056239 adds up prime indices, row sums of A112798.
%Y A344652 A325534 counts separable partitions, ranked by A335433.
%Y A344652 A325535 counts inseparable partitions, ranked by A335448.
%Y A344652 A335452 counts anti-run permutations of prime indices.
%Y A344652 A345170 counts partitions with a wiggly permutation, ranked by A345172.
%Y A344652 A345192 counts non-wiggly compositions, ranked by A345168.
%Y A344652 Counting compositions by patterns:
%Y A344652 - A102726 avoiding (1,2,3).
%Y A344652 - A128761 avoiding (1,2,3) adjacent.
%Y A344652 - A335514 matching (1,2,3).
%Y A344652 - A344614 avoiding (1,2,3) and (3,2,1) adjacent.
%Y A344652 - A344615 weakly avoiding (1,2,3) adjacent.
%Y A344652 Cf. A001222, A003242, A056986, A316524, A333213, A335511, A344604, A344653, A344654, A345167, A345173.
%K A344652 nonn
%O A344652 1,6
%A A344652 _Gus Wiseman_, Jun 17 2021