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 A356233 #6 Aug 30 2022 09:41:27 %S A356233 1,1,1,2,1,2,1,3,2,1,1,4,1,1,2,5,1,4,1,2,1,1,1,7,2,1,3,2,1,4,1,7,1,1, %T A356233 2,9,1,1,1,3,1,2,1,2,4,1,1,12,2,2,1,2,1,7,1,3,1,1,1,8,1,1,2,11,1,2,1, %U A356233 2,1,2,1,16,1,1,4,2,2,2,1,5,5,1,1,4,1,1 %N A356233 Number of integer factorizations of n into gapless numbers (A066311). %C A356233 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. We define a number to be gapless (listed by A066311) iff its prime indices cover an interval of positive integers. %e A356233 The counted factorizations of n = 2, 4, 8, 12, 24, 36, 48: %e A356233 (2) (4) (8) (12) (24) (36) (48) %e A356233 (2*2) (2*4) (2*6) (3*8) (4*9) (6*8) %e A356233 (2*2*2) (3*4) (4*6) (6*6) (2*24) %e A356233 (2*2*3) (2*12) (2*18) (3*16) %e A356233 (2*2*6) (3*12) (4*12) %e A356233 (2*3*4) (2*2*9) (2*3*8) %e A356233 (2*2*2*3) (2*3*6) (2*4*6) %e A356233 (3*3*4) (3*4*4) %e A356233 (2*2*3*3) (2*2*12) %e A356233 (2*2*2*6) %e A356233 (2*2*3*4) %e A356233 (2*2*2*2*3) %t A356233 primeMS[n_]:=If[n==1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]]; %t A356233 facs[n_]:=If[n<=1,{{}},Join@@Table[Map[Prepend[#,d]&,Select[facs[n/d],Min@@#>=d&]],{d,Rest[Divisors[n]]}]]; %t A356233 sqq[n_]:=Max@@Differences[primeMS[n]]<=1; %t A356233 Table[Length[Select[facs[n],And@@sqq/@#&]],{n,100}] %Y A356233 The shortest of these factorizations is listed at A356234, length A287170. %Y A356233 A000005 counts divisors. %Y A356233 A001055 counts factorizations. %Y A356233 A001221 counts distinct prime factors, sum A001414. %Y A356233 A003963 multiplies together the prime indices. %Y A356233 A132747 counts non-isolated divisors, complement A132881. %Y A356233 A356069 counts gapless divisors, initial A356224 (complement A356225). %Y A356233 A356226 lists the lengths of maximal gapless submultisets of prime indices: %Y A356233 - length: A287170 %Y A356233 - minimum: A356227 %Y A356233 - maximum: A356228 %Y A356233 - bisected length: A356229 %Y A356233 - standard composition: A356230 %Y A356233 - Heinz number: A356231 %Y A356233 - positions of first appearances: A356232 %Y A356233 Cf. A001222, A060680-A060683, A073491-A073495, A193829, A328195, A328335-A328458. %K A356233 nonn %O A356233 1,4 %A A356233 _Gus Wiseman_, Aug 28 2022