OFFSET
1,2
FORMULA
The inclusive version is a(n+1) - 1.
EXAMPLE
The non-prime-powers (exclusive) are 1, 6, 10, 12, 14, 15, 18, 20, ... which increase by more than 1 after positions 1, 2, 3, 4, 6, 7, ...
MATHEMATICA
ce=Select[Range[100], !PrimePowerQ[#]&];
Select[Range[Length[ce]-1], !ce[[#+1]]==ce[[#]]+1&]
KEYWORD
nonn
AUTHOR
Gus Wiseman, Sep 12 2024
STATUS
approved