OFFSET
1,1
COMMENTS
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..100
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.
MATHEMATICA
emrp[p_]:=Module[{rev=IntegerReverse[p]}, If[rev!=p&&PrimeQ[rev], Max[ rev, p], Nothing]]; Select[Union[emrp/@Prime[Range[7500]]], OddQ[Sqrt[8(#-IntegerReverse[ #])+1]]&] (* Harvey P. Dale, Jan 30 2023 *)
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Jonathan Vos Post, Oct 02 2012
EXTENSIONS
More terms from Alois P. Heinz, Oct 03 2012
STATUS
approved