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 A097823 Numbers n such that n^2+n+41 (Euler's "prime generating polynomial") is not squarefree. 10
 40, 603, 798, 890, 917, 1245, 1253, 1318, 1640, 1651, 1721, 2010, 2069, 2251, 2452, 2606, 2649, 3094, 3099, 3321, 3402, 3527, 3607, 4123, 4239, 4301, 4819, 4943, 5002, 5083, 5308, 5372, 5425, 5736, 5790, 5930, 5958, 5998, 6150, 6416, 6511, 6683, 6764 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Harvey P. Dale, Table of n, a(n) for n = 1..1000 Eric Weisstein's World of Mathematics, Prime-Generating Polynomial EXAMPLE a(1)=40: p(40)=40^2+40+41=1681=41^2, a(2)=603: p(603)=364253=197*43^2, a(11)=1721: p(1721)=2963603=43*41^3, a(68)=10428: p(10428)=108753653=743^2*197, a(91)=14144: p(14144)=200066921=47^4*41. MATHEMATICA Select[Range[10000], !SquareFreeQ[#^2+#+41]&] (* Harvey P. Dale, Nov 06 2011 *) CROSSREFS Cf. A013929 n is not squarefree, A002837 n such that n^2-n+41 is prime, A007634 n such that n^2+n+41 is composite, A005846 primes of form n^2+n+41, A097822 n^2+n+41 has more than 2 prime factors. Sequence in context: A159946 A185744 A269497 * A263953 A002847 A057808 Adjacent sequences:  A097820 A097821 A097822 * A097824 A097825 A097826 KEYWORD nonn AUTHOR Hugo Pfoertner, Aug 26 2004 STATUS approved

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Last modified June 16 19:49 EDT 2021. Contains 345068 sequences. (Running on oeis4.)