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 A228122 Smallest nonnegative number x such that x^2 + x + 41 has exactly n prime factors counting multiplicities. 4
 0, 40, 420, 1721, 14144, 139563, 3019035, 24304266, 206583092, 3838101265 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Table of n, a(n) for n=1..10. EXAMPLE a(1) = 0 because if x = 0 then x^2 + x + 41 = 41, which has 1 prime factor. a(2) = 40 because if x = 40 then x^2 + x + 41 = 1681 = 41*41, which has 2 prime factors, counting multiplicities. a(3) = 420 because if x = 420 then x^2 + x + 41 = 176861 = 47*53*71, which has 3 prime factors. MATHEMATICA a = {}; Do[x = 0; While[PrimeOmega[x^2 + x + 41] != k, x++]; AppendTo[a, x], {k, 9}]; a PROG (PARI) a(n) = {my(m=0); while (bigomega(m^2+m+41) != n, m++); m; } \\ Michel Marcus, Jan 31 2016 (Python) from sympy import factorint def A228122(n): k = 0 while sum(factorint(k*(k+1)+41).values()) != n: k += 1 return k # Chai Wah Wu, Sep 07 2018 CROSSREFS Cf. A005846, A007634, A145292, A145293, A056561. Sequence in context: A168192 A251129 A007772 * A247408 A285855 A210355 Adjacent sequences: A228119 A228120 A228121 * A228123 A228124 A228125 KEYWORD nonn,more AUTHOR Shyam Sunder Gupta, Aug 11 2013 EXTENSIONS a(9) from Zak Seidov, Feb 01 2016 a(10) from Giovanni Resta, Sep 08 2018 STATUS approved

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Last modified November 28 17:03 EST 2023. Contains 367419 sequences. (Running on oeis4.)