

A178322


Numbers n such that 156/101*(10^(4n)1)1 is prime.


2



1, 2, 5, 29, 30, 108, 679, 4478, 8736, 17000, 22427, 22731
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,2


COMMENTS

If n is in the sequence then m=91*(156/101*(10^(4n)1)1) is a term of A072394. Namely if n is a term of this sequence then for m=1/101*(14196*10^(4n)23387), we have sigma(m)=reversal(m)m (see comment lines of A072394).
Numbers corresponding to the larger terms are probable primes.
Next term exceeds 3500.  Robert G. Wilson v, Aug 08 2011.
a(13) > 40000.  Robert Price, May 23 2014


LINKS

Table of n, a(n) for n=1..12.


MATHEMATICA

Select[Range[700], PrimeQ[156/101*(10^(4 #)  1)  1] &]


CROSSREFS

Cf. A072394, A178321.
Sequence in context: A248235 A327345 A049050 * A165161 A098858 A213995
Adjacent sequences: A178319 A178320 A178321 * A178323 A178324 A178325


KEYWORD

more,nonn


AUTHOR

Farideh Firoozbakht, May 26 2010


EXTENSIONS

a(8)a(12) from Robert Price, May 23 2014


STATUS

approved



