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A069987
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Squarefree numbers of form n^2 + 1.
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3
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2, 5, 10, 17, 26, 37, 65, 82, 101, 122, 145, 170, 197, 226, 257, 290, 362, 401, 442, 485, 530, 577, 626, 677, 730, 785, 842, 901, 962, 1090, 1157, 1226, 1297, 1370, 1522, 1601, 1765, 1937, 2026, 2117, 2210, 2305, 2402, 2501, 2602, 2705, 2810, 2917, 3026
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 1..1000
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FORMULA
| a(n) = A049533(n)^2+1.
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MATHEMATICA
| Select[ Range[10^4], IntegerQ[ Sqrt[ # - 1]] && Union[ Transpose[ FactorInteger[ # ]] [[2]]] [[ -1]] == 1 &]
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PROG
| (PARI) for(n=1, 100, if(issquarefree(n^2+1)==1, print1(n^2+1, ", ")))
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CROSSREFS
| Cf. A059591, A002496, A124809, A005117, A002522.
Sequence in context: A082607 A159547 A002522 * A119114 A062493 A056871
Adjacent sequences: A069984 A069985 A069986 * A069988 A069989 A069990
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KEYWORD
| nonn,changed
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AUTHOR
| Sharon Sela (sharonsela(AT)hotmail.com), May 01 2002
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EXTENSIONS
| Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Benoit Cloitre (benoit7848c(AT)orange.fr) and Vladeta Jovovic (vladeta(AT)eunet.rs), May 04 2002
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