OFFSET
1,1
MATHEMATICA
lpf[n_] := FactorInteger[n][[1, 1]];
b[n_] := b[n] = If[n == 1, 4, b[n-1]+lpf[b[n-1]^2-1]-1];
a[n_] := lpf[b[n]^2-1];
Table[a[n], {n, 1, 85}] (* Jean-François Alcover, May 13 2023 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Shevelev, May 15 2010
EXTENSIONS
A 7 replaced by 17 and sequence extended by R. J. Mathar, May 31 2010
STATUS
approved