

A138143


Triangle read by rows in which row n lists p(1), p(2), ..., p(n), p(n1), ..., p(1), where p(i) = ith 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
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OFFSET

1,1


COMMENTS

Row n contains 2n1 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



