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A114263 Smallest number m such that prime(n) + 2*prime(n+m) is a prime. 3
1, 1, 1, 1, 1, 4, 5, 3, 2, 2, 3, 1, 1, 4, 5, 1, 5, 4, 2, 2, 2, 2, 1, 3, 1, 1, 8, 4, 1, 1, 2, 3, 9, 2, 5, 2, 2, 9, 6, 1, 1, 1, 1, 2, 3, 4, 1, 4, 5, 8, 11, 1, 11, 4, 5, 1, 4, 1, 5, 8, 1, 1, 1, 1, 2, 5, 1, 5, 9, 2, 1, 10, 3, 4, 4, 5, 5, 6, 7, 4, 1, 1, 2, 4, 13, 6, 6, 6, 7, 9, 1, 3, 1, 7, 3, 9, 1, 3, 3, 6, 3, 8, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET
2,6
LINKS
EXAMPLE
n=2: prime(2)+2*prime(2+1)=3+2*5=13 is prime, so a(2)=1;
n=3: prime(3)+2*prime(3+1)=5+2*7=19 is prime, so a(2)=1;
...
n=7: prime(7)+2*prime(7+1)=17+2*19=55 is not prime
...
prime(7)+2*prime(7+4)=17+2*31=79 is prime, so a(7)=4;
MATHEMATICA
Table[p1 = Prime[n1]; n2 = 1; p2 = Prime[n1 + n2]; While[cp = p1 + 2* p2; ! PrimeQ[cp], n2++; p2 = Prime[n1 + n2]]; n2, {n1, 2, 201}]
PROG
(Haskell)
a114263 n = head [m | m <- [1..n],
a010051 (a000040 n + 2 * a000040 (n + m)) == 1]
-- Reinhard Zumkeller, Oct 31 2013
CROSSREFS
Sequence in context: A244144 A201337 A291083 * A094850 A163973 A369500
KEYWORD
easy,nonn
AUTHOR
Lei Zhou, Nov 20 2005
EXTENSIONS
Edited definition to conform to OEIS style. - Reinhard Zumkeller, Oct 31 2013
STATUS
approved

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Last modified May 27 01:42 EDT 2024. Contains 372847 sequences. (Running on oeis4.)