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 A111676 Array of primes of the type k concatenated with 2n-1 where k < 2n-1. 1---> no prime 13,23 5---> no prime 17,37,47,67 19,29,59,79,89 211,311,811,911 113,313,613,1013,1213 15---> no prime 317,617,... ... Sequence contains the arrays separated by zero for n = 10k +5. 2

%I

%S 0,13,23,0,17,37,47,67,19,29,59,79,89,211,311,811,911,113,313,613,

%T 1013,1213,0,317,617,1117,1217,419,619,719,919,1019,1319,1619,421,521,

%U 821,1021,1321,1621,1721,223,523,823,1123,1223,1423,1523,1723,1823,0,127

%N Array of primes of the type k concatenated with 2n-1 where k < 2n-1. 1---> no prime 13,23 5---> no prime 17,37,47,67 19,29,59,79,89 211,311,811,911 113,313,613,1013,1213 15---> no prime 317,617,... ... Sequence contains the arrays separated by zero for n = 10k +5.

%e For 2n-1 = 9, we have primes 19,29,59,79 and 89. 109 is not included as 10 > 9.

%p cat2 := proc(n,m) n*10^(max(1,ilog10(m)+1))+m ; end: A111676 := proc(nrow) local town1,k,a ; town1 := 2*nrow-1 ; a := [] ; for k from 1 to town1-1 do if isprime(cat2(k,town1)) then a := [op(a),cat2(k,town1)] ; fi ; od; if a = [] then RETURN([0]) ; else RETURN(a) ; fi ; end: seq(op(A111676(nrow)),nrow=1..16) ; # _R. J. Mathar_, Aug 20 2007

%Y Cf. A111677.

%K base,nonn,tabf

%O 1,2

%A _Amarnath Murthy_, Aug 16 2005

%E More terms from _R. J. Mathar_, Aug 20 2007

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Last modified March 26 15:32 EDT 2023. Contains 361549 sequences. (Running on oeis4.)