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A076056 Primes which when read backwards are composite numbers. 7
19, 23, 29, 41, 43, 47, 53, 59, 61, 67, 83, 89, 103, 109, 127, 137, 139, 163, 173, 193, 197, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 317, 331, 349, 367, 379, 397, 401, 409, 419, 421, 431, 433, 439, 443, 449, 457 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Subsidiary sequences that could be added:(1) Start of the first occurrence of n consecutive primes in the above sequence. (2) Start of the first occurrence of n consecutive primes with digit reversal also a prime.
The subsidiary sequence (1) with the indices at which n>=2 consecutive primes are first found in this sequence is 1, 1, 4, 4, 4, 4, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44, ... - R. J. Mathar, May 22 2009
Subsequence of A151768. - Reinhard Zumkeller, Jul 06 2009
LINKS
Anders Hellström, Sage program
MATHEMATICA
Select[Prime[Range[100]], !PrimeQ[FromDigits[Reverse[IntegerDigits[ # ]]]]&]
PROG
(Magma) [p: p in PrimesUpTo(500)|not IsPrime(Seqint(Reverse(Intseq(p))))]; // Vincenzo Librandi, Jun 03 2019
CROSSREFS
Cf. A076055.
Complement of A007500 with respect to A000040. [From Reinhard Zumkeller, Jul 06 2009]
Sequence in context: A151768 A270083 A286333 * A068654 A286415 A305835
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Oct 04 2002
EXTENSIONS
More terms from Harvey P. Dale, Oct 11 2002
STATUS
approved

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Last modified April 15 20:47 EDT 2024. Contains 371696 sequences. (Running on oeis4.)