OFFSET
1,2
LINKS
Éric Angelini, Sums of distinct prime factors, Personal blog, December 2023.
EXAMPLE
a(1) + a(2) = 1 + 14 = 15 whose sopf is 8, a perfect cube.
a(2) + a(3) = 14 + 31 = 45 whose sopf is 8, a perfect cube.
a(5) + a(6) = 91 + 92 = 183 whose sopf is 64, a perfect cube.
MATHEMATICA
a[1]=1; a[n_]:=a[n]=(k=1; While[MemberQ[ar=Array[a, n-1], k]|| !IntegerQ[Total[First/@FactorInteger[k+a[n-1]]]^(1/3)], k++]; k); Array[a, 70]
CROSSREFS
KEYWORD
nonn
AUTHOR
Giorgos Kalogeropoulos and Eric Angelini, Dec 05 2023
STATUS
approved