A037231 Primes which set a new record for length of Pratt certificate.

2, 3, 7, 23, 43, 139, 283, 659, 1319, 5179, 9227, 23159, 55399, 148439, 366683, 793439, 1953839, 4875119, 9750239, 27353747, 71815607, 192287243, 430893643

Offset: 1

Author

David W. Wilson

Keywords

• nonn
• more

Links

• Eric Weisstein's World of Mathematics, Pratt Certificate.

Crossrefs

Cf. A037202.

Programs

Mathematica

a[1] = 1; a[n_] := a[n] = 1 + Plus @@ (a@ PrimePi@ # & /@ First /@ FactorInteger[ Prime@ n - 1]); t = Table[ 0, {25}]; k = 2; While[k < 23420001, b = a[k]/2; If[b < 1001 && t[[b]] == 0, t[[b]] = Prime@ k; Print[{b, Prime@ k }]]; k++]; t