A154530 Primes that are a concatenation of 2*k and 2*k+1 or 2*k and 2*k-1 for some k.
23, 43, 67, 89, 109, 1213, 2221, 2423, 3433, 3637, 4241, 4243, 5051, 5657, 5857, 6263, 6869, 7069, 7877, 7879, 8081, 8887, 9091, 9293, 9697, 10099, 102101, 102103, 108107, 108109, 112111, 114113, 120121, 124123, 126127, 138139, 148147, 150151
Offset: 1
Examples
2*1=2, 2*1+1=3, and 23 the concatenation of 2 and 3 is prime, so a(1)=23
Links
- Pierre CAMI, Table of n, a(n) for n=1..10153
Programs
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Haskell
a154530 n = a154530_list !! (n-1) a154530_list = filter ((== 1) . a010051') a248378_list -- Reinhard Zumkeller, Jun 27 2015
Extensions
Edited by Charles R Greathouse IV, Apr 28 2010