login
A244624
Consider the number of lines in the Pratt certificate for the n-th prime (A037202). This sequence shows where 2n first occurs.
0
1, 2, 4, 9, 14, 34, 61, 120, 215, 690, 1144, 2584, 5626, 13709, 31275, 63461, 145767, 340332, 649190, 1703684, 4218462, 10675070, 22892978
OFFSET
0,2
COMMENTS
See comment section of A037202.
a(n) ~ 2*a(n-1).
FORMULA
Also PrimePi( A037231 ).
MATHEMATICA
a[1] = 1; a[n_] := a[n] = 1 + Plus @@ (a@ PrimePi@# & /@ First /@ FactorInteger[ Prime@ n - 1]); k = 1; t = Table[0, {1000}]; While[k < 1000000000000001, If[a@ k < 1001 && t[[a[k]/2]] == 0, t[[a[k]/2]] = k; Print[{a@k, k}]]; k++]; t
CROSSREFS
Sequence in context: A341959 A173407 A113862 * A343592 A036277 A042960
KEYWORD
nonn,more
AUTHOR
STATUS
approved