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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
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
Sequence in context: A272704 A272737 A273533 * A145812 A220944 A200879
KEYWORD
nonn,base
AUTHOR
K. D. Bajpai, Jan 24 2016
STATUS
approved

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Last modified April 14 16:48 EDT 2024. Contains 371666 sequences. (Running on oeis4.)