OFFSET
1,2
COMMENTS
EXAMPLE
The sequence of terms together with their prime indices begins:
1: {}
15: {2,3}
42: {1,2,4}
54: {1,2,2,2}
100: {1,1,3,3}
132: {1,1,2,5}
312: {1,1,1,2,6}
560: {1,1,1,1,3,4}
720: {1,1,1,1,2,2,3}
816: {1,1,1,1,2,7}
1824: {1,1,1,1,1,2,8}
3520: {1,1,1,1,1,1,3,5}
4416: {1,1,1,1,1,1,2,9}
6272: {1,1,1,1,1,1,1,4,4}
8064: {1,1,1,1,1,1,1,2,2,4}
10368: {1,1,1,1,1,1,1,2,2,2,2}
11136: {1,1,1,1,1,1,1,2,10}
16640: {1,1,1,1,1,1,1,1,3,6}
23808: {1,1,1,1,1,1,1,1,2,11}
38400: {1,1,1,1,1,1,1,1,1,2,3,3}
MATHEMATICA
primeMS[n_]:=If[n==1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
Select[Range[10000], Times@@primeMS[#]==Total[primeMS[#]]+1&]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Mar 25 2019
STATUS
approved