OFFSET
-1,1
EXAMPLE
The sequence of terms together with their prime signatures begins:
30: (1,1,1)
6: (1,1)
1: ()
72: (3,2)
144: (4,2)
216: (3,3)
576: (6,2)
360: (3,2,1)
2304: (8,2)
840: (3,1,1,1)
720: (4,2,1)
1728: (6,3)
1080: (3,3,1)
1260: (2,2,1,1)
147456: (14,2)
6912: (8,3)
1800: (3,2,2)
2160: (4,3,1)
MATHEMATICA
dat=Table[DivisorSigma[0, n]-PrimeOmega[n]*PrimeNu[n], {n, 1000}];
Table[Position[dat, i][[1, 1]], {i, First[Split[Union[dat], #2==#1+1&]]}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Nov 02 2019
STATUS
approved