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%I #28 Apr 08 2018 15:38:14
%S 7,17,47,97,167,257,367,497,647,817,1007,1217,1447,1697,1967,2257,
%T 2567,2897,3247,3617,4007,4417,4847,5297,5767,6257,6767,7297,7847,
%U 8417,9007,9617,10247,10897,11567,12257,12967,13697,14447,15217,16007,16817
%N a(n) = 10 * n^2 + 7.
%C Initially this sequence is rich in primes. First 7 terms are all prime numbers. But the 8th term 491 is a composite number equal to 7 * 71. The first 28 terms are primes or semiprimes. - _Kausthub Gudipati_, Sep 25 2011
%H Harry J. Smith, <a href="/A061722/b061722.txt">Table of n, a(n) for n = 0..1000</a>
%H T. Trotter, Jr, <a href="http://www.trottermath.net/numthry/trotprims1.html">Trotter Numbers & Trotter Primes</a> [Warning: As of March 2018 this site appears to have been hacked. Proceed with great caution. The original content should be retrieved from the Wayback machine and added here. - _N. J. A. Sloane_, Mar 29 2018]
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F a(n) = 10 * n^2 + 7.
%F G.f.: ( -7+4*x-17*x^2 ) / (x-1)^3 . - _R. J. Mathar_, Feb 27 2015
%o (PARI) { for (n=1, 1000, write("b061722.txt", n, " ", 10*n^2 + 7) ) } \\ _Harry J. Smith_, Jul 27 2009
%Y Cf. A061679, A195905.
%K easy,nonn
%O 0,1
%A _Terrel Trotter, Jr._, Jun 20 2001
%E Definition revised by _Omar E. Pol_, Aug 04 2009
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