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 A340105 #10 Mar 17 2021 08:02:15
%S A340105 1,7,13,19,23,29,37,43,47,53,61,71,73,79,89,91,97,101,103,107,113,131,
%T A340105 133,137,139,149,151,161,163,167,173,181,193,197,199,203,223,227,229,
%U A340105 233,239,247,251,257,259,263,269,271,281,293,299,301,307,311,313,317
%N A340105 Odd products of distinct primes of nonprime index (A007821).
%C A340105 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.
%F A340105 Equals A005117 /\ A005408 /\ A320628 = A005117 /\ A320629.
%e A340105 The sequence of terms together with the corresponding sets of multisets begins:
%e A340105 1: {} 91: {{1,1},{1,2}} 173: {{1,1,1,3}}
%e A340105 7: {{1,1}} 97: {{3,3}} 181: {{1,2,4}}
%e A340105 13: {{1,2}} 101: {{1,6}} 193: {{1,1,5}}
%e A340105 19: {{1,1,1}} 103: {{2,2,2}} 197: {{2,2,3}}
%e A340105 23: {{2,2}} 107: {{1,1,4}} 199: {{1,9}}
%e A340105 29: {{1,3}} 113: {{1,2,3}} 203: {{1,1},{1,3}}
%e A340105 37: {{1,1,2}} 131: {{1,1,1,1,1}} 223: {{1,1,1,1,2}}
%e A340105 43: {{1,4}} 133: {{1,1},{1,1,1}} 227: {{4,4}}
%e A340105 47: {{2,3}} 137: {{2,5}} 229: {{1,3,3}}
%e A340105 53: {{1,1,1,1}} 139: {{1,7}} 233: {{2,7}}
%e A340105 61: {{1,2,2}} 149: {{3,4}} 239: {{1,1,6}}
%e A340105 71: {{1,1,3}} 151: {{1,1,2,2}} 247: {{1,2},{1,1,1}}
%e A340105 73: {{2,4}} 161: {{1,1},{2,2}} 251: {{1,2,2,2}}
%e A340105 79: {{1,5}} 163: {{1,8}} 257: {{3,5}}
%e A340105 89: {{1,1,1,2}} 167: {{2,6}} 259: {{1,1},{1,1,2}}
%t A340105 Select[Range[1,100,2],SquareFreeQ[#]&&FreeQ[If[#==1,{},FactorInteger[#]],{p_,k_}/;PrimeQ[PrimePi[p]]]&]
%Y A340105 These primes (of nonprime index) are listed by A007821.
%Y A340105 The non-strict version is A320629, with not necessarily odd version A320628.
%Y A340105 The not necessarily odd version is A340104.
%Y A340105 The prime instead of odd nonprime version:
%Y A340105 primes: A006450
%Y A340105 products: A076610
%Y A340105 strict: A302590
%Y A340105 The squarefree semiprime instead of odd nonprime version:
%Y A340105 strict: A309356
%Y A340105 primes: A322551
%Y A340105 products: A339113
%Y A340105 The semiprime instead of odd nonprime version:
%Y A340105 primes: A106349
%Y A340105 products: A339112
%Y A340105 strict: A340020
%Y A340105 A001358 lists semiprimes.
%Y A340105 A056239 gives the sum of prime indices, which are listed by A112798.
%Y A340105 A257994 counts prime prime indices.
%Y A340105 A302242 is the weight of the multiset of multisets with MM-number n.
%Y A340105 A305079 is the number of connected components for MM-number n.
%Y A340105 A330944 counts nonprime prime indices.
%Y A340105 A330945 lists numbers with a nonprime prime index (nonprime case: A330948).
%Y A340105 A339561 lists products of distinct squarefree semiprimes.
%Y A340105 MM-numbers: A255397 (normal), A302478 (set multisystems), A320630 (set multipartitions), A302494 (sets of sets), A305078 (connected), A316476 (antichains), A318991 (chains), A320456 (covers), A328514 (connected sets of sets), A329559 (clutters), A340019 (half-loop graphs).
%Y A340105 Cf. A000040, A000720, A001055, A001222, A003963, A005117, A007097, A018252, A289509, A320461, A320631, A320911, A320912.
%K A340105 nonn
%O A340105 1,2
%A A340105 _Gus Wiseman_, Mar 12 2021