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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
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, 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, 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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

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

Triangle of primes mentioned in A061802.

LINKS

Table of n, a(n) for n=1..100.

EXAMPLE

Triangle begins:

.............. 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

MATHEMATICA

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 *)

CROSSREFS

Cf. A000040, A061802, A066622, A037126.

Sequence in context: A054483 A258568 A108939 * A285727 A281908 A106441

Adjacent sequences:  A138140 A138141 A138142 * A138144 A138145 A138146

KEYWORD

easy,nonn,tabf

AUTHOR

Omar E. Pol, Mar 09 2008

EXTENSIONS

Edited by N. J. A. Sloane, Apr 07 2008, Nov 15 2008

STATUS

approved

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Last modified April 25 13:31 EDT 2019. Contains 322461 sequences. (Running on oeis4.)