A015975 First k>n, not a power of n+1 or one of its prime factors, such that k | n^k + 1.

171, 10, 205, 21, 203, 10, 57, 82, 253, 111, 1027, 34, 45, 226, 6029713, 21, 7558979, 55, 63, 26, 1081, 39, 55, 626, 63, 50, 1172383, 45, 126883, 74, 99, 50, 175, 1191, 164317, 50, 63, 55, 104263, 58, 44419, 50, 75, 1081, 30973, 50, 34591207, 1405, 57

Offset

2,1

Links

Table of n, a(n) for n=2..50.

Example

a(3) = 10 because 3^10 + 1 = 59050 which is divisible by 10 and ten is not a power of 3+1 or 4.

Mathematica

Do[ k = n + 2; f = Transpose[ FactorInteger[ n + 1 ] ] [ [ 1 ] ]; l = Length[ f ]; While[ PowerMod[ n, k, k ] != k - 1 || Union[ Table[ IntegerQ[ Log[ f[ [ m ] ], k ] ], {m, 1, l} ] ] != {False}, k++ ]; Print[ k ], {n, 2, 47} ]

Crossrefs

Sequence in context: A187704 A263059 A243294 * A292090 A186871 A185614

Adjacent sequences: A015972 A015973 A015974 * A015976 A015977 A015978

Keyword

nonn

Author

Robert G. Wilson v

Status

approved