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A105318
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Starting prime for the smallest prime Pythagorean sequence for n triangles.
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4
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OFFSET
| 1,1
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COMMENTS
| Smallest prime p(0) such that the n-chain governed by recurrence p(i+1)=(p(i)^2 + 1)/2 are all primes. Equivalently, least prime p(0) that generates a sequence of n 2-prime triangles, where p(k) is the hypotenuse of the k-th triangle and the leg of the (k+1)-th triangle.
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LINKS
| H. Dubner, Posting to Number Theory List
T. Forbes, Posting to Number Theory List
H. Dubner & T. Forbes, Prime Pythagorean Triangles
T. Forbes, Posting to Number Theory List
H. Dubner & T. Forbes, Journal of Integer Sequences, Vol. 4(2001) #01.2.3, Prime Pythagorean triangles
C. K. Caldwell, The Prime Glossary, Pythagorean triples
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EXAMPLE
| 5 is a(1) because (5^2+1)/2 = 13 is prime, but (13^2+1)/2 = 85 is not.
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CROSSREFS
| Cf. A048270; A048295.
Sequence in context: A048885 A002208 A100653 * A121021 A159799 A185579
Adjacent sequences: A105315 A105316 A105317 * A105319 A105320 A105321
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KEYWORD
| hard,more,nonn
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AUTHOR
| Lekraj Beedassy (blekraj(AT)yahoo.com), Apr 26 2005
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EXTENSIONS
| a(1) added by T. D. Noe (noe(AT)sspectra.com), Jan 29 2011
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