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 A241570 Primes of the form: (concatenation of first n positive integers) - 1. 1
 11, 123456789101112131415161717 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Next term, if it exists, has more than 1000 digits. LINKS Table of n, a(n) for n=1..2. EXAMPLE 11 in this sequence because 12-1 is prime. MATHEMATICA Select[Table[FromDigits[Flatten[IntegerDigits[Range[n]]]] - 1, {n, 1, 100}], PrimeQ] (* after Bruno Berselli *) PROG (Magma) c:=0; for d in [1..3] do m:=10^d; for n in [m div 10..m-1] do c:=c*m+n; t:=c-1; if IsPrime(t) then t; end if; end for; end for; // after Jon E. Schoenfield CROSSREFS Cf. A241569. Sequence in context: A004022 A243534 A257304 * A083344 A294889 A308425 Adjacent sequences: A241567 A241568 A241569 * A241571 A241572 A241573 KEYWORD nonn,base,more,bref AUTHOR Vincenzo Librandi, Apr 26 2014 STATUS approved

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Last modified September 10 19:41 EDT 2024. Contains 375794 sequences. (Running on oeis4.)