id:A104172 - OEIS Search Results

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Replace nonprimes in A005185 by zeros.

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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 (list; graph; listen)

	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.` `Adjacent sequences: A104169 A104170 A104171 this_sequence A104173 A104174 A104175` `Sequence in context: A021815 A075255 A135498 this_sequence A091408 A106242 A121474`
	KEYWORD	`nonn`
	AUTHOR	`Roger Bagula (rlbagulatftn(AT)yahoo.com), Mar 10 2005`

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Last modified November 8 07:45 EST 2009. Contains 166143 sequences.

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