cp's OEIS Frontend

A333146 Number of non-unimodal negated permutations of the multiset of prime indices of n.

%I A333146 #5 Feb 16 2025 08:33:59
%S A333146 0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,2,0,0,0,1,0,2,0,0,0,0,
%T A333146 0,3,0,0,0,2,0,2,0,1,1,0,0,3,0,0,0,1,0,0,0,2,0,0,0,8,0,0,1,0,0,2,0,1,
%U A333146 0,2,0,7,0,0,0,1,0,2,0,3,0,0,0,8,0,0,0
%N A333146 Number of non-unimodal negated permutations of the multiset of prime indices of n.
%C A333146 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.
%C A333146 A sequence of integers is unimodal if it is the concatenation of a weakly increasing and a weakly decreasing sequence.
%H A333146 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/UnimodalSequence.html">Unimodal Sequence</a>
%F A333146 a(n) + A333145(n) = A008480(n).
%e A333146 The a(n) permutations for n = 12, 24, 36, 60, 72, 90, 96:
%e A333146   (121)  (1121)  (1212)  (1132)  (11212)  (1232)  (111121)
%e A333146          (1211)  (1221)  (1213)  (11221)  (1322)  (111211)
%e A333146                  (2121)  (1231)  (12112)  (2132)  (112111)
%e A333146                          (1312)  (12121)  (2231)  (121111)
%e A333146                          (1321)  (12211)  (2312)
%e A333146                          (2131)  (21121)  (2321)
%e A333146                          (2311)  (21211)
%e A333146                          (3121)
%t A333146 primeMS[n_]:=If[n==1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
%t A333146 unimodQ[q_]:=Or[Length[q]<=1,If[q[[1]]<=q[[2]],unimodQ[Rest[q]],OrderedQ[Reverse[q]]]];
%t A333146 Table[Length[Select[Permutations[primeMS[n]],!unimodQ[-#]&]],{n,30}]
%Y A333146 Dominated by A008480.
%Y A333146 The non-negated version is A332671.
%Y A333146 A more interesting version is A332742.
%Y A333146 The complement is counted by A333145.
%Y A333146 Unimodal compositions are A001523.
%Y A333146 Unimodal normal sequences are A007052.
%Y A333146 Compositions whose negation is unimodal are A332578.
%Y A333146 Partitions with unimodal negated run-lengths are A332638.
%Y A333146 Numbers with non-unimodal negated unsorted prime signature are A332642.
%Y A333146 Cf. A056239, A112798, A115981, A124010, A328509, A332283, A332288, A332294, A332639, A332669, A332670, A332741.
%K A333146 nonn
%O A333146 1,24
%A A333146 _Gus Wiseman_, Mar 09 2020