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A138143 Triangle read by rows in which row n lists p(1), p(2), ..., p(n), p(n-1), ..., p(1), where p(i) = i-th prime. 3

%I

%S 2,2,3,2,2,3,5,3,2,2,3,5,7,5,3,2,2,3,5,7,11,7,5,3,2,2,3,5,7,11,13,11,

%T 7,5,3,2,2,3,5,7,11,13,17,13,11,7,5,3,2,2,3,5,7,11,13,17,19,17,13,11,

%U 7,5,3,2,2,3,5,7,11,13,17,19,23,19,17,13,11,7,5,3,2,2,3,5,7,11,13,17,19,23,29,23,19,17,13,11,7,5,3,2

%N Triangle read by rows in which row n lists p(1), p(2), ..., p(n), p(n-1), ..., p(1), where p(i) = i-th prime.

%C Row n contains 2n-1 terms and each column lists the prime numbers A000040.

%C Triangle of primes mentioned in A061802.

%e Triangle begins:

%e .............. 2

%e ........... 2, 3, 2

%e ........ 2, 3, 5, 3, 2

%e ..... 2, 3, 5, 7, 5, 3, 2

%e .. 2, 3, 5, 7,11, 7, 5, 3, 2

%t nn=10;Module[{pr=Prime[Range[nn]],e},Flatten[Table[e=Take[pr,n];Join[ e,Reverse[Most[e]]],{n,nn}]]] (* _Harvey P. Dale_, Mar 14 2015 *)

%Y Cf. A000040, A061802, A066622, A037126.

%K easy,nonn,tabf

%O 1,1

%A _Omar E. Pol_, Mar 09 2008

%E Edited by _N. J. A. Sloane_, Apr 07 2008, Nov 15 2008

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Last modified May 24 18:34 EDT 2019. Contains 323534 sequences. (Running on oeis4.)