OFFSET
1,1
COMMENTS
This sequence contains all unimodal composites (numbers whose list of prime factors is strictly increasing then strictly decreasing).
EXAMPLE
90 is the first member of this sequence because its prime factor decomposition is 2*3^2*5, using the three smallest primes and 3^2 = 9 is the first power of 3 greater than 5 (and 2).
MATHEMATICA
Module[{pfl},
Select[Range[2000],
Function[n, pfl = Power @@@ FactorInteger[n];
1 < First[First[Position[pfl, Max[pfl], 1]]] < Length[pfl]]]]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Olivier Gérard, Dec 30 2014
STATUS
approved