OFFSET
1,2
COMMENTS
EXAMPLE
The terms (center), their binary indices (left), and their weakly decreasing prime indices (right) begin:
{1} 1 ()
{2} 2 (1)
{1,2} 3 (2)
{3} 4 (1,1)
{1,3} 5 (3)
{4} 8 (1,1,1)
{1,4} 9 (2,2)
{3,4} 12 (2,1,1)
{1,2,3,4} 15 (3,2)
{5} 16 (1,1,1,1)
{1,5} 17 (7)
{3,5} 20 (3,1,1)
{1,3,5} 21 (4,2)
{1,3,4,5} 29 (10)
{6} 32 (1,1,1,1,1)
{3,6} 36 (2,2,1,1)
{2,4,6} 42 (4,2,1)
{1,2,4,6} 43 (14)
{1,3,4,6} 45 (3,2,2)
{2,3,4,6} 46 (9,1)
{1,2,3,4,6} 47 (15)
{5,6} 48 (2,1,1,1,1)
MATHEMATICA
prix[n_]:=If[n==1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
bix[n_]:=Join@@Position[Reverse[IntegerDigits[n, 2]], 1];
Select[Range[100], OddQ[Total[bix[#]]+Total[prix[#]]]&]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, May 14 2024
STATUS
approved