

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
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OFFSET

1,1


LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000
Eric Weisstein's World of Mathematics, PrimeGenerating 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^2n+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



