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 A349150 #7 Nov 13 2021 10:22:44 %S A349150 1,2,3,5,6,7,9,11,13,14,15,17,18,19,21,23,26,27,29,31,33,35,37,38,39, %T A349150 41,42,43,45,47,49,51,53,54,57,58,59,61,63,65,67,69,71,73,74,77,78,79, %U A349150 81,83,86,87,89,91,93,95,97,98,99,101,103,105,106,107,109 %N A349150 Heinz numbers of integer partitions with at most one odd part. %C A349150 The Heinz number of a partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k), so these are numbers with at most one odd prime index. %C A349150 Also Heinz numbers of partitions with conjugate alternating sum <= 1. %F A349150 Union of A066207 (no odd parts) and A349158 (one odd part). %e A349150 The terms and their prime indices begin: %e A349150 1: {} 23: {9} 49: {4,4} %e A349150 2: {1} 26: {1,6} 51: {2,7} %e A349150 3: {2} 27: {2,2,2} 53: {16} %e A349150 5: {3} 29: {10} 54: {1,2,2,2} %e A349150 6: {1,2} 31: {11} 57: {2,8} %e A349150 7: {4} 33: {2,5} 58: {1,10} %e A349150 9: {2,2} 35: {3,4} 59: {17} %e A349150 11: {5} 37: {12} 61: {18} %e A349150 13: {6} 38: {1,8} 63: {2,2,4} %e A349150 14: {1,4} 39: {2,6} 65: {3,6} %e A349150 15: {2,3} 41: {13} 67: {19} %e A349150 17: {7} 42: {1,2,4} 69: {2,9} %e A349150 18: {1,2,2} 43: {14} 71: {20} %e A349150 19: {8} 45: {2,2,3} 73: {21} %e A349150 21: {2,4} 47: {15} 74: {1,12} %t A349150 primeMS[n_]:=If[n==1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]]; %t A349150 Select[Range[100],Count[Reverse[primeMS[#]],_?OddQ]<=1&] %Y A349150 The case of no odd parts is A066207, counted by A000041 up to 0's. %Y A349150 Requiring all odd parts gives A066208, counted by A000009. %Y A349150 These partitions are counted by A100824, even-length case A349149. %Y A349150 These are the positions of 0's and 1's in A257991. %Y A349150 The conjugate partitions are ranked by A349151. %Y A349150 The case of one odd part is A349158, counted by A000070 up to 0's. %Y A349150 A056239 adds up prime indices, row sums of A112798. %Y A349150 A122111 is a representation of partition conjugation. %Y A349150 A300063 ranks partitions of odd numbers, counted by A058695 up to 0's. %Y A349150 A316524 gives the alternating sum of prime indices (reverse: A344616). %Y A349150 A325698 ranks partitions with as many even as odd parts, counted by A045931. %Y A349150 A340932 ranks partitions whose least part is odd, counted by A026804. %Y A349150 A345958 ranks partitions with alternating sum 1. %Y A349150 A349157 ranks partitions with as many even parts as odd conjugate parts. %Y A349150 Cf. A000290, A000700, A001222, A027187, A027193, A028260, A035363, A047993, A215366, A257992, A277579, A326841. %K A349150 nonn %O A349150 1,2 %A A349150 _Gus Wiseman_, Nov 10 2021