A270840 Numbers n such that n^3 + 1 is a 2-pseudoprime (or Sarrus number).

12, 36, 138, 270, 546, 4800, 7560, 12840, 14700, 358200, 678480, 16139970, 22934100, 55058580, 59553720, 74371320, 113068380, 116605860, 242699310, 997521210, 1592680320, 1652749200, 3190927740, 5088964800, 6974736756, 9214178820

Offset

1,1

Comments

Since n^3 + 1 is clearly composite (n>1), this is n such that 2^(n^3) == 1 (mod n^3+1).

There is only one n such that n + 1 is a composite number up to 10^10: 14700. - Altug Alkan, Mar 27 2016

Links

Table of n, a(n) for n=1..26.

Formula

a(n) = A265653(n) - 1. - Altug Alkan, Mar 24 2016

Prog

(PARI) is(n)=Mod(2, n^3+1)^(n^3)==1

Crossrefs

Cf. A001567, A135590, A265653.

Sequence in context: A355386 A073403 A191817 * A064518 A238923 A135178

Adjacent sequences: A270837 A270838 A270839 * A270841 A270842 A270843

Keyword

nonn

Author

Jeppe Stig Nielsen, Mar 23 2016

Extensions

More terms from Altug Alkan, Mar 24 2016

Status

approved