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A037231 Primes which set a new record for length of Pratt certificate. 3
2, 3, 7, 23, 43, 139, 283, 659, 1319, 5179, 9227, 23159, 55399, 148439, 366683, 793439, 1953839, 4875119, 9750239, 27353747, 71815607, 192287243, 430893643 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..23.

Eric Weisstein's World of Mathematics, Definition

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

CROSSREFS

Cf. A037202.

Sequence in context: A106865 A267504 A000057 * A248525 A082449 A129741

Adjacent sequences:  A037228 A037229 A037230 * A037232 A037233 A037234

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified December 7 05:14 EST 2019. Contains 329839 sequences. (Running on oeis4.)