login
A104172
Replace nonprimes in A005185 with zeros.
0
0, 0, 2, 3, 3, 0, 5, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 11, 11, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 17, 17, 0, 0, 19, 0, 0, 0, 0, 23, 23, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 31, 0, 0, 0, 0, 0, 37, 0, 0, 0, 0, 0, 0, 0, 41, 43, 0, 43, 43, 0, 0, 0, 47, 47, 0, 0, 0, 0, 0, 0, 0, 0, 41
OFFSET
0,3
FORMULA
a(n) = if Hofstadter[n] is prime then Hofstadter[n] else zero
MATHEMATICA
digits = 200 Hofstadter[n_Integer? Positive] := Hofstadter[n] = Hofstadter[n - Hofstadter[n - 1]] + Hofstadter[n - Hofstadter[n - 2]] Hofstadter[0] = Hofstadter[1] = 1 b = Table[If[PrimeQ[ Hofstadter[n]] == True, Hofstadter[n], 0], {n, 0, digits - 1}]
CROSSREFS
Cf. A005185.
Sequence in context: A359788 A075255 A135498 * A091408 A193382 A106242
KEYWORD
nonn
AUTHOR
Roger L. Bagula, Mar 10 2005
STATUS
approved