

A005542


Numbers n such that 10*3^n  1 is prime.
(Formerly M0589)


0



1, 2, 3, 4, 8, 10, 14, 20, 22, 26, 30, 38, 39, 49, 54, 58, 70, 81, 84, 87, 102, 111, 140, 159, 207, 224, 328, 358, 360, 447, 484, 908, 1083, 1242, 1461, 1705, 4624, 5199, 7106, 8667, 11157, 13130, 28052, 30483, 32166, 34447, 36986, 86578, 89940, 120433, 140743, 147308, 159276, 165543
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OFFSET

1,2


COMMENTS

a(56) > 2*10^5.  Robert Price, Mar 16 2014
All terms are verified primes (ie, not probable primes)  Robert Price, Mar 16 2014


REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).


LINKS

Table of n, a(n) for n=1..54.
H. C. Williams and C. R. Zarnke, Some prime numbers of the forms 2*3^n+1 and 2*3^n1, Math. Comp., 26 (1972), 995998.


MATHEMATICA

Do[ If[ PrimeQ[ 10*3^n  1], Print[n] ], {n, 1, 12901} ]


PROG

(PARI) v=[ ]; for(n=1, 1900, if(isprime(10*3^n1), v=concat(v, n), )); v


CROSSREFS

Sequence in context: A302406 A328092 A242762 * A037171 A308811 A295296
Adjacent sequences: A005539 A005540 A005541 * A005543 A005544 A005545


KEYWORD

hard,nonn


AUTHOR

N. J. A. Sloane.


EXTENSIONS

More terms from Robert G. Wilson v, Feb 05 2001
a(42)a(55) from Robert Price, Mar 16 2014


STATUS

approved



