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.

A342193 Numbers with no prime index dividing all the other prime indices.

This page as a plain text file.
%I A342193 #13 Apr 17 2021 01:57:16
%S A342193 1,15,33,35,45,51,55,69,75,77,85,91,93,95,99,105,119,123,135,141,143,
%T A342193 145,153,155,161,165,175,177,187,195,201,203,205,207,209,215,217,219,
%U A342193 221,225,231,245,247,249,253,255,265,275,279,285,287,291,295,297,299
%N A342193 Numbers with no prime index dividing all the other prime indices.
%C A342193 Alternative name: 1 and numbers with smallest prime index not dividing all the other prime indices.
%C A342193 First differs from A339562 in having 45.
%C A342193 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 A342193 Also 1 and Heinz numbers of integer partitions with smallest part not dividing all the others (counted by A338470). The Heinz number of a partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k), giving a bijective correspondence between positive integers and integer partitions.
%e A342193 The sequence of terms together with their prime indices begins:
%e A342193       1: {}         105: {2,3,4}      201: {2,19}
%e A342193      15: {2,3}      119: {4,7}        203: {4,10}
%e A342193      33: {2,5}      123: {2,13}       205: {3,13}
%e A342193      35: {3,4}      135: {2,2,2,3}    207: {2,2,9}
%e A342193      45: {2,2,3}    141: {2,15}       209: {5,8}
%e A342193      51: {2,7}      143: {5,6}        215: {3,14}
%e A342193      55: {3,5}      145: {3,10}       217: {4,11}
%e A342193      69: {2,9}      153: {2,2,7}      219: {2,21}
%e A342193      75: {2,3,3}    155: {3,11}       221: {6,7}
%e A342193      77: {4,5}      161: {4,9}        225: {2,2,3,3}
%e A342193      85: {3,7}      165: {2,3,5}      231: {2,4,5}
%e A342193      91: {4,6}      175: {3,3,4}      245: {3,4,4}
%e A342193      93: {2,11}     177: {2,17}       247: {6,8}
%e A342193      95: {3,8}      187: {5,7}        249: {2,23}
%e A342193      99: {2,2,5}    195: {2,3,6}      253: {5,9}
%t A342193 Select[Range[100],#==1||With[{p=PrimePi/@First/@FactorInteger[#]},!And@@IntegerQ/@(p/Min@@p)]&]
%Y A342193 The complement is counted by A083710 (strict: A097986).
%Y A342193 The complement with no 1's is A083711 (strict: A098965).
%Y A342193 These partitions are counted by A338470 (strict: A341450).
%Y A342193 The squarefree case is A339562, with squarefree complement A339563.
%Y A342193 The case with maximum prime index not divisible by all others is A343338.
%Y A342193 The case with maximum prime index divisible by all others is A343339.
%Y A342193 A000005 counts divisors.
%Y A342193 A000070 counts partitions with a selected part.
%Y A342193 A001221 counts distinct prime factors.
%Y A342193 A006128 counts partitions with a selected position (strict: A015723).
%Y A342193 A056239 adds up prime indices, row sums of A112798.
%Y A342193 A299702 lists Heinz numbers of knapsack partitions.
%Y A342193 A339564 counts factorizations with a selected factor.
%Y A342193 Cf. A066637, A072774, A098743, A253249, A264401, A257993, A342050, A342051, A343344.
%K A342193 nonn
%O A342193 1,2
%A A342193 _Gus Wiseman_, Apr 11 2021