

A217286


Larger of pairs of emirps (A006567) whose difference with the (smaller) reversal is a triangular number (A000217).


3



73, 1811, 7817, 7927, 11701, 12611, 14431, 14831, 15101, 15241, 15541, 15601, 16111, 16451, 16651, 17021, 18671, 18731, 19181, 19541, 19681, 19841, 32213, 32713, 33223, 33623, 33923, 35803, 36013, 36353, 36913, 37123, 37363, 37463, 37963, 39383, 39983, 71707
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OFFSET

1,1


COMMENTS

Related to A217386 as triangular numbers (A000217) are to squares (A000290), but in the current sequence, only the larger of each emirp pair is used.


LINKS

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


FORMULA

{k: k is in A006567 and k  A004086(k) is in A000217}.


EXAMPLE

a(1) = 73 because 73  37 = 36 = 8th triangular number.
a(2) = 1811 because R(1811) = A004086(1811) = 1181, and 1811  1181 = 630 = 35th triangular number.
a(3) = 7817 because 7817  7187 = 630 = 35th triangular number.
a(4) = 7927 because 7927  7297 = 630 = 35*36/2.


CROSSREFS

Cf. A000217, A004086, A006567, A217386.
Sequence in context: A197241 A332948 A224505 * A282784 A332912 A017789
Adjacent sequences: A217283 A217284 A217285 * A217287 A217288 A217289


KEYWORD

nonn,base,easy


AUTHOR

Jonathan Vos Post, Oct 02 2012


EXTENSIONS

More terms from Alois P. Heinz, Oct 03 2012


STATUS

approved



