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A089761
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Smallest k such that k*i^2 + 1 is prime for i = 1 to n.
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0
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1, 1, 4, 22, 58, 58, 58, 54972, 68112, 4748632, 861066640, 861066640, 861066640, 861066640, 861066640
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| a(16) > 1.4*10^13 [From Max Alekseyev (maxale(AT)gmail.com)]
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MAPLE
| for n from 1 to 10 do for k from 1 do f:=0: for i from 1 to n do if not isprime(k*i^2+1) then f:=1: break fi od: if f=0 then printf("%d, ", k): break fi od od: (C. Ronaldo)
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CROSSREFS
| Sequence in context: A050773 A122241 A076525 * A098837 A104171 A036924
Adjacent sequences: A089758 A089759 A089760 * A089762 A089763 A089764
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KEYWORD
| hard,more,nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Nov 22 2003
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EXTENSIONS
| Corrected and extended by C. Ronaldo (aga_new_ac(AT)hotmail.com), Dec 26 2004
a(11)-a(15) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Sep 27 2008
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