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A062223
Numbers k such that the smoothly undulating palindromic number (74*10^k - 47)/99 is a prime.
0
5, 17, 2069, 6815, 20417, 25745
OFFSET
1,1
COMMENTS
Prime versus probable prime status and proofs are given in the author's table.
No further terms < 100000. - Ray Chandler, Aug 17 2011
EXAMPLE
k=17 -> (74*10^17 - 47)/99 = 74747474747474747.
CROSSREFS
KEYWORD
nonn,base,more
AUTHOR
Patrick De Geest and Hans Rosenthal (Hans.Rosenthal(AT)t-online.de), Jun 15 2001
EXTENSIONS
Edited by Ray Chandler, Aug 17 2011
STATUS
approved