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Search: id:A117854
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| A117854 |
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Let p(n) be the nth-prime. Sequence gives primes of the form | p(n)*p(n+2) - p(n+1)*p(n+3)| +1. |
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+0
2
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| 37, 97, 61, 163, 199, 337, 353, 461, 379, 719, 1021, 421, 1753, 811, 577, 1607, 1423, 1949, 3121, 2141, 3943, 4549, 4243, 4969, 2801, 4261, 4357, 3767, 4621, 5647, 6917, 4603, 3697, 6491, 5653, 7019, 6841, 5153, 5261, 12163, 6121, 3301, 11587, 11887
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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a(n) = | p(n)*p(n+2) - p(n+1)*p(n+3) | +1
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EXAMPLE
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7, 11, 13, 17 --> | 7*13-11*17 | + 1 = 97
19, 23, 29, 31 --> | 19*29 - 23*31 | + 1 = 163
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MAPLE
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P:=proc(n) local i, j; for i from 1 by 1 to n do j:=abs(ithprime(i)*ithprime(i+2)-ithprime(i+1)*ithprime(i+3))+1; if isprime(j) then print(j); fi; od; end: P(1000);
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CROSSREFS
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Adjacent sequences: A117851 A117852 A117853 this_sequence A117855 A117856 A117857
Sequence in context: A044556 A142525 A132360 this_sequence A033222 A098025 A142793
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KEYWORD
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easy,nonn
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AUTHOR
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Paolo P. Lava and Giorgio Balzarotti (ppl(AT)spl.at), May 02 2006
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