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 A244991 #16 Feb 11 2021 22:59:56
%S A244991 2,4,5,8,10,11,15,16,17,20,22,23,25,30,31,32,33,34,40,41,44,45,46,47,
%T A244991 50,51,55,59,60,62,64,66,67,68,69,73,75,77,80,82,83,85,88,90,92,93,94,
%U A244991 97,99,100,102,103,109,110,115,118,119,120,121,123,124,125,127,128
%N A244991 Numbers whose greatest prime factor is a prime with an odd index; n such that A006530(n) is in A031368.
%C A244991 Equally, numbers n for which A061395(n) is odd.
%C A244991 A122111 maps each one of these numbers to a unique term of A026424 and vice versa.
%C A244991 If the Heinz number of a partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k), these are the Heinz numbers of partitions whose greatest part is odd, counted by A027193. - _Gus Wiseman_, Feb 08 2021
%H A244991 Antti Karttunen, <a href="/A244991/b244991.txt">Table of n, a(n) for n = 1..10001</a>
%F A244991 For all n, A244989(a(n)) = n.
%e A244991 From _Gus Wiseman_, Feb 08 2021: (Start)
%e A244991 The sequence of terms together with their prime indices begins:
%e A244991 2: {1} 32: {1,1,1,1,1} 64: {1,1,1,1,1,1}
%e A244991 4: {1,1} 33: {2,5} 66: {1,2,5}
%e A244991 5: {3} 34: {1,7} 67: {19}
%e A244991 8: {1,1,1} 40: {1,1,1,3} 68: {1,1,7}
%e A244991 10: {1,3} 41: {13} 69: {2,9}
%e A244991 11: {5} 44: {1,1,5} 73: {21}
%e A244991 15: {2,3} 45: {2,2,3} 75: {2,3,3}
%e A244991 16: {1,1,1,1} 46: {1,9} 77: {4,5}
%e A244991 17: {7} 47: {15} 80: {1,1,1,1,3}
%e A244991 20: {1,1,3} 50: {1,3,3} 82: {1,13}
%e A244991 22: {1,5} 51: {2,7} 83: {23}
%e A244991 23: {9} 55: {3,5} 85: {3,7}
%e A244991 25: {3,3} 59: {17} 88: {1,1,1,5}
%e A244991 30: {1,2,3} 60: {1,1,2,3} 90: {1,2,2,3}
%e A244991 31: {11} 62: {1,11} 92: {1,1,9}
%e A244991 (End)
%t A244991 Select[Range[100],OddQ[PrimePi[FactorInteger[#][[-1,1]]]]&] (* _Gus Wiseman_, Feb 08 2021 *)
%o A244991 (Scheme, with Antti Karttunen's IntSeq-library)
%o A244991 (define A244991 (MATCHING-POS 1 1 (COMPOSE odd? A061395)))
%Y A244991 Complement: A244990.
%Y A244991 Cf. A006530, A026424, A031368, A122111, A244321, A244322, A244989.
%Y A244991 Looking at least instead of greatest prime index gives A026804.
%Y A244991 The partitions with these Heinz numbers are counted by A027193.
%Y A244991 The case where Omega is odd also is A340386.
%Y A244991 A001222 counts prime factors.
%Y A244991 A056239 adds up prime indices.
%Y A244991 A300063 ranks partitions of odd numbers.
%Y A244991 A061395 selects maximum prime index.
%Y A244991 A066208 ranks partitions into odd parts.
%Y A244991 A112798 lists the prime indices of each positive integer.
%Y A244991 A340931 ranks odd-length partitions of odd numbers.
%Y A244991 Cf. A000009, A058695, A072233, A160786, A300272, A340101, A340385, A340604.
%K A244991 nonn
%O A244991 1,1
%A A244991 _Antti Karttunen_, Jul 21 2014