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A034816
Concatenations C1 and C2 are both prime (see the comment lines).
0
9, 51, 63, 117, 123, 157, 183, 213, 217, 219, 257, 263, 321, 327, 333, 423, 441, 473, 541, 597, 621, 687, 693, 723, 777, 879, 909, 987, 1101, 1143, 1187, 1387, 1459, 1551, 1887, 2127, 2179, 2193, 2817, 3197, 3339, 3513, 3633, 4029, 4209, 4429, 4529, 4557
OFFSET
0,1
COMMENTS
C1 = 'prevprime(n) followed by n'
C2 = 'n followed by nextprime(n)'
EXAMPLE
n=1551 -> previous prime is 1549, next prime is 1553, thus '15491551' and '15511553' are both primes.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, Oct 15 1998
STATUS
approved