

A061722


a(n) = 10 * n^2 + 7.


3



7, 17, 47, 97, 167, 257, 367, 497, 647, 817, 1007, 1217, 1447, 1697, 1967, 2257, 2567, 2897, 3247, 3617, 4007, 4417, 4847, 5297, 5767, 6257, 6767, 7297, 7847, 8417, 9007, 9617, 10247, 10897, 11567, 12257, 12967, 13697, 14447, 15217, 16007, 16817
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OFFSET

0,1


COMMENTS

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


LINKS

Harry J. Smith, Table of n, a(n) for n = 0..1000
T. Trotter, Jr, Trotter Numbers & Trotter Primes [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]
Index entries for linear recurrences with constant coefficients, signature (3,3,1).


FORMULA

a(n) = 10 * n^2 + 7.
G.f.: ( 7+4*x17*x^2 ) / (x1)^3 .  R. J. Mathar, Feb 27 2015


PROG

(PARI) { for (n=1, 1000, write("b061722.txt", n, " ", 10*n^2 + 7) ) } \\ Harry J. Smith, Jul 27 2009


CROSSREFS

Cf. A061679, A195905.
Sequence in context: A179030 A179031 A107178 * A195905 A104164 A192244
Adjacent sequences: A061719 A061720 A061721 * A061723 A061724 A061725


KEYWORD

easy,nonn


AUTHOR

Terrel Trotter, Jr., Jun 20 2001


EXTENSIONS

Definition revised by Omar E. Pol, Aug 04 2009


STATUS

approved



