OFFSET
1,1
COMMENTS
EXAMPLE
The sequence of terms together with their prime indices begins:
4: {1,1}
24: {1,1,1,2}
27: {2,2,2}
36: {1,1,2,2}
54: {1,2,2,2}
80: {1,1,1,1,3}
200: {1,1,1,3,3}
224: {1,1,1,1,1,4}
240: {1,1,1,1,2,3}
360: {1,1,1,2,2,3}
405: {2,2,2,2,3}
500: {1,1,3,3,3}
540: {1,1,2,2,2,3}
600: {1,1,1,2,3,3}
625: {3,3,3,3}
672: {1,1,1,1,1,2,4}
675: {2,2,2,3,3}
704: {1,1,1,1,1,1,5}
784: {1,1,1,1,4,4}
810: {1,2,2,2,2,3}
900: {1,1,2,2,3,3}
MATHEMATICA
Select[Range[2, 1000], With[{f=FactorInteger[#]}, PrimePi[f[[-1, 1]]]==Total[Last/@f]-Length[f]]&]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Mar 06 2019
STATUS
approved