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 A019549 Primes formed by concatenating other primes. 10
 23, 37, 53, 73, 113, 137, 173, 193, 197, 211, 223, 227, 229, 233, 241, 257, 271, 277, 283, 293, 311, 313, 317, 331, 337, 347, 353, 359, 367, 373, 379, 383, 389, 397, 433, 523, 541, 547, 557, 571, 577, 593, 613, 617, 673, 677, 719, 727, 733, 743, 757, 761, 773, 797, 977 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 REFERENCES Sylvester Smith, "A Set of Conjectures on Smarandache Sequences", Bulletin of Pure and Applied Sciences, (Bombay, India), Vol. 15 E (No. 1), 1996, pp. 101-107. LINKS M. F. Hasler, Table of n, a(n) for n = 1..17495 EXAMPLE 113 is member as 11 and 3 are primes. a(12)=227 = "2"+"2"+"7" is the first term not in A105184 (restricted to concatenation of two primes). [From M. F. Hasler, Oct 15 2009] PROG (PARI) is_A019549(n, recurse=0)={ isprime(n) == recurse & return(recurse); for(i=1, #Str(n)-1, isprime( n%10^i ) & is_A019549( n\10^i, 1) & n\10^(i-1)%10 & return(1)) } [Hasler] CROSSREFS Cf. A105184, A152242. Sequence in context: A051362 A034302 A057878 * A272157 A129800 A105184 Adjacent sequences:  A019546 A019547 A019548 * A019550 A019551 A019552 KEYWORD nonn,base AUTHOR R. Muller STATUS approved

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