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A175191 a(n) = the smallest positive integer such that (the n-th prime)+2*a(n) is composite. 2
1, 3, 2, 1, 2, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Every term except a(2) (which is 3) is either 1 or 2.
LINKS
MAPLE
a:= n-> `if`(n=2, 3, `if`(isprime(ithprime(n)+2), 2, 1)):
seq(a(n), n=1..105); # Alois P. Heinz, Oct 02 2020
MATHEMATICA
spi[n_]:=Module[{i=1}, While[PrimeQ[Prime[n]+2i], i++]; i]; Array[spi, 110] (* Harvey P. Dale, Apr 23 2012 *)
CROSSREFS
Sequence in context: A181715 A077089 A156352 * A328928 A370560 A342468
KEYWORD
nonn
AUTHOR
Leroy Quet, Mar 01 2010
EXTENSIONS
Extended by Ray Chandler, Mar 04 2010
STATUS
approved

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Last modified July 21 16:28 EDT 2024. Contains 374475 sequences. (Running on oeis4.)