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 A268033 Numbers n such that concatenating prime(n) with n^2 is prime. 1
 3, 9, 11, 29, 33, 39, 121, 153, 177, 179, 187, 193, 207, 231, 261, 291, 357, 361, 423, 471, 487, 507, 543, 579, 621, 627, 633, 641, 659, 683, 699, 737, 773, 843, 863, 879, 907, 933, 957, 1009, 1011, 1023, 1049, 1051, 1099, 1101, 1107, 1131, 1191, 1327, 1387, 1403 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS All the terms in this sequence are odd numbers. LINKS K. D. Bajpai, Table of n, a(n) for n = 1..10000 EXAMPLE 9 appears in the sequence because prime(9) || 9^2 = 2381 which is prime. 11 appears in the sequence because prime(11) || 11^2 = 31121 which is prime. MAPLE select(n -> andmap(isprime, parse(cat(ithprime(n), n^2))), [seq(n, n=1..5000)]); MATHEMATICA Select[Range[5000], PrimeQ[FromDigits[Flatten[{IntegerDigits[Prime[#]], IntegerDigits[#^2]}]]] &] PROG (PARI) for (n = 1, 1000, if(isprime(k=eval(Str(prime(n), n^2))), print1(n, ", "))) (MAGMA) [n:n in[1..500]|IsPrime(m) where m is Seqint(Intseq(n^2) cat Intseq(NthPrime(n)))]; CROSSREFS Cf. A000040, A000290. Sequence in context: A272704 A272737 A273533 * A145812 A220944 A200879 Adjacent sequences:  A268030 A268031 A268032 * A268034 A268035 A268036 KEYWORD nonn,base AUTHOR K. D. Bajpai, Jan 24 2016 STATUS approved

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Last modified December 16 20:51 EST 2018. Contains 318189 sequences. (Running on oeis4.)