

A117300


Consider all pairs (p,q) of consecutive primes such that p and q both have k digits and qp = k; sequence lists the values of q.


2



3, 13, 19, 31, 43, 61, 73, 1013, 1091, 1097, 1217, 1283, 1301, 1307, 1427, 1433, 1451, 1487, 1493, 1553, 1571, 1583, 1601, 1613, 1667, 1697, 1787, 1871, 1877, 1997, 2003, 2087, 2141, 2207, 2243, 2273, 2297, 2351, 2381, 2393, 2441, 2477, 2543, 2621, 2663
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OFFSET

1,1


LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..10000


EXAMPLE

31 is in the sequence because (1) it is a 2digit prime number, (2) the previous 2digit prime number is 29 and (3) 3129=2
1451 is in the sequence because (1) it is a 4digit prime number, (2) the previous 4digit prime number is 1447 and (3) 14511447=4


MATHEMATICA

Transpose[Select[Partition[Prime[Range[400]], 2, 1], IntegerLength[#[[1]]] == IntegerLength[#[[2]]]&&#[[2]]#[[1]]==IntegerLength[#[[1]]]&]][[2]] (* Harvey P. Dale, Nov 01 2015 *)


CROSSREFS

Cf. A117155.
Sequence in context: A168425 A252090 A079419 * A023215 A185069 A023239
Adjacent sequences: A117297 A117298 A117299 * A117301 A117302 A117303


KEYWORD

base,nonn


AUTHOR

Luc Stevens (lms022(AT)yahoo.com), Apr 21 2006


EXTENSIONS

Edited by N. J. A. Sloane, Apr 29 2007
Corrected by Harvey P. Dale, Nov 01 2015


STATUS

approved



