A180471 Irregular triangle in which row n has all primes q such that prime(n)*q is a base-2 Fermat pseudoprime.

31, 257, 73, 89, 683, 113, 11, 151, 331, 73, 109, 61681, 127, 337, 5419, 178481, 2796203, 157, 1613, 233, 1103, 2089, 3033169, 1321, 20857, 599479, 281, 86171, 122921, 19, 37, 109, 433, 38737, 2731, 8191, 121369, 22366891, 13367, 164511353, 8831418697, 23, 353, 397, 683, 2113, 2931542417

Offset

5,1

Comments

The length of row n is A085014(n). The smallest and largest primes in row n are A085012(n) and A085019(n).

References

See A085012.

Links

Amiram Eldar, Table of n, a(n) for n = 5..3424

Index entries for sequences related to pseudoprimes

Example

The irregular triangle begins
31
none
257
73
89, 683
113
11, 151, 331
73, 109
61681

Mathematica

Flatten[Table[p=Prime[n]; q=Transpose[FactorInteger[2^(p-1)-1]][[1]]; cnt={}; Do[If[PowerMod[2, p*q[[i]]-1, p*q[[i]]]==1, AppendTo[cnt, q[[i]]]], {i, Length[q]}]; cnt, {n, 5, 50}]]

Crossrefs

Cf. A085012, A085014, A085019.

Sequence in context: A042872 A142623 A089705 * A125368 A126526 A008386

Adjacent sequences: A180468 A180469 A180470 * A180472 A180473 A180474

Keyword

nonn,tabf

Author

T. D. Noe, Jan 19 2011

Status

approved