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A244369
Palindromic right-angled primes.
3
101, 787, 34543, 7654567, 345676543, 34567876543
OFFSET
1,1
COMMENTS
Intersection of A002113 and A167842.
Intersection of A002385 and A135602.
The last term of this sequence is also the last term of A134811.
EXAMPLE
Illustration of a(6) = 34567876543, the last term of this sequence:
. . . . . . . . . . .
. . . . . 8 . . . . .
. . . . 7 . 7 . . . .
. . . 6 . . . 6 . . .
. . 5 . . . . . 5 . .
. 4 . . . . . . . 4 .
3 . . . . . . . . . 3
. . . . . . . . . . .
. . . . . . . . . . .
. . . . . . . . . . .
PROG
(Python)
from sympy import isprime
A244369 = []
for n in range(1, 10):
....for m in range(n-1, -1, -1):
........l = ''.join([str(d) for d in range(n, m-1, -1)])
........p = int(l+l[-2::-1])
........if isprime(p):
............A244369.append(p)
....for m in range(n+1, 10):
........l = ''.join([str(d) for d in range(n, m+1)])
........p = int(l+l[-2::-1])
........if isprime(p):
............A244369.append(p)
A244369 = sorted(A244369) # Chai Wah Wu, Aug 15 2014
CROSSREFS
KEYWORD
nonn,base,fini,full
AUTHOR
Omar E. Pol, Jun 26 2014
STATUS
approved