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A322098
a(1)=1, a(2)=1; for n > 2, a(n) is the largest noncomposite proper divisor of the concatenation of terms a(1) through a(n-1).
1
1, 1, 1, 37, 43, 439, 31321, 3555900001, 3555900001, 3563253697383401592719, 3563253697383401592719, 2069957682701324503311258278145695430463576158940397351, 7609174114451381087553287043297264970128251910800933517241956209
OFFSET
1,4
MATHEMATICA
FromDigits /@ Nest[Append[#, IntegerDigits@ Select[Divisors[FromDigits[Join @@ #]], ! CompositeQ@ # &][[-1]] ] &, {{1}, {1}, {1}}, 7] (* Michael De Vlieger, Nov 26 2018 *)
CROSSREFS
Cf. A322097.
Sequence in context: A186281 A225423 A367478 * A039351 A043174 A043954
KEYWORD
nonn,base
AUTHOR
John Mason, Nov 26 2018
EXTENSIONS
a(12) corrected and a(13) added by Daniel Suteu, Jan 19 2019
STATUS
approved