OFFSET
1,1
COMMENTS
Also numbers whose alternating sum of prime indices is < 0. Equivalently, numbers with even bigomega whose conjugate prime indices are not all even. This is the intersection of A028260 and A000037. - Gus Wiseman, Jun 20 2021
EXAMPLE
From Gus Wiseman, Jun 20 2021: (Start)
The sequence of terms together with their prime indices begins:
6: {1,2} 51: {2,7} 86: {1,14}
10: {1,3} 54: {1,2,2,2} 87: {2,10}
14: {1,4} 55: {3,5} 88: {1,1,1,5}
15: {2,3} 56: {1,1,1,4} 90: {1,2,2,3}
21: {2,4} 57: {2,8} 91: {4,6}
22: {1,5} 58: {1,10} 93: {2,11}
24: {1,1,1,2} 60: {1,1,2,3} 94: {1,15}
26: {1,6} 62: {1,11} 95: {3,8}
33: {2,5} 65: {3,6} 96: {1,1,1,1,1,2}
34: {1,7} 69: {2,9} 104: {1,1,1,6}
35: {3,4} 74: {1,12} 106: {1,16}
38: {1,8} 77: {4,5} 111: {2,12}
39: {2,6} 82: {1,13} 115: {3,9}
40: {1,1,1,3} 84: {1,1,2,4} 118: {1,17}
46: {1,9} 85: {3,7} 119: {4,7}
(End)
MATHEMATICA
Select[Range[200], And@@EvenQ[{PrimeOmega[#], DivisorSigma[0, #]}]&] (* Harvey P. Dale, Jan 24 2013 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jun 04 2006
STATUS
approved