OFFSET
1,1
COMMENTS
All terms > 2 are congruent to 7 (mod 10).
Corresponding n's are: 1, 6, 76, 96, 106, 116, 166, 186, 206, 246, 266, 286, 316, 356, 376, 386, 396, 446, 456, 486, 516, 536, 586, 726, 736, 746, 766, 796, 846, 866, 906, 916, 1036, 1046, 1076, 1116, 1126, 1156, 1176, 1236, 1296, 1316, 1326, 1406, 1456, 1546, 1586, 1596, 1686, 1706, 1786, 1816, 1896, 1926, 1956, all are congruent to 1 (mod 5).
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
MATHEMATICA
Select[Table[(1 + 2 n + 3 n^2 + 4 n^3)/5, {n, 0, 200}], PrimeQ] (* Vincenzo Librandi, Mar 21 2013 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Zak Seidov, Sep 27 2006
STATUS
approved