Search: id:A127698
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%I A127698
%S A127698 0,2,6,12,11,66,33,110,99,99,110,132,165,110,606,141,767,504,342,281,
%T A127698 222,363,605,948,303,848,504,1251,1010,969,1029,1190,1353,726,1190,666,
%U A127698 1332,1010,888,867,848,1029,1212,1595,1089,6336,2882,9339,7887,6446
%N A127698 Sum of n-th triangular number and its reversal (leading zeros not truncated).
%C A127698 Gupta states in Prime Curios: "The smallest odd prime which can be represented 
               as sum of a triangular number and its reverse, i.e., 10 + 01 = 11." 
               Note that this is not the definition of digital reversal, R(n), which 
               truncates leading zeros, used in A004086 and other sequences.
%D A127698 Angell, I. O. and Godwin, H. J. "On Truncatable Primes." Math. Comput. 
               31, 265-267, 1977.
%H A127698 <a href="Sindx_Tri.html#tprime">Index entries for sequences related to 
               truncatable primes</a>
%H A127698 G. L. Honaker, Jr. and Chris Caldwell, eds., <a href="http://primes.utm.edu/
               curios/page.php?short=11">11</a>.
%F A127698 a(n) = A000217(n) + pseudoreversal(A000217(n)) where pseudoreversal(n) 
               is the digital reversal with leading zeros left intact (not truncated).
%e A127698 a(0) = 0 + 0 = 0.
%e A127698 a(1) = 1 + 1 = 2 is the even prime.
%e A127698 a(4) = 10 + 01 = 11 is an odd prime.
%e A127698 a(5) = 15 + 51 = 66 = A000217(10).
%e A127698 a(19) = 190 + 091 = 281 is an odd prime.
%e A127698 a(24) = 300 + 003 = 303.
%e A127698 a(35) = 630 + 036 = 666 = A000217(36).
%Y A127698 Cf. A000217, A004086.
%Y A127698 Sequence in context: A145103 A009230 A069491 this_sequence A130503 A074385 
               A057340
%Y A127698 Adjacent sequences: A127695 A127696 A127697 this_sequence A127699 A127700 
               A127701
%K A127698 base,easy,nonn
%O A127698 0,2
%A A127698 Jonathan Vos Post (jvospost3(AT)gmail.com), Apr 03 2007

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