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A116301 n times n+1 gives the concatenation of two numbers m and m+2.

%I A116301 #5 Aug 20 2019 11:18:23
%S A116301 768,859,911,3286,6714,45453,54547,990101,8181820,70588234,343130555,
%T A116301 362637364,363636362,420053632,421052633,497975710,502024290,
%U A116301 578947367,579946368,636363638,637362636,656869445,706766919
%N A116301 n times n+1 gives the concatenation of two numbers m and m+2.
%H A116301 Robert Israel, <a href="/A116301/b116301.txt">Table of n, a(n) for n = 1..9000</a>
%p A116301 As:= {}:
%p A116301 for m from 2 to 20 do
%p A116301    acands:= map(t -> rhs(op(t)), [msolve(a*(a+1)=2, 10^m+1)]);
%p A116301    bcands:= map(t -> t*(t+1) mod 10^m, acands);
%p A116301    good:= select(t -> bcands[t]>=10^(m-1), [$1..nops(acands)]);
%p A116301    As:= As union convert(acands[good],set);
%p A116301 od:
%p A116301 sort(convert(As,list)); # _Robert Israel_, Aug 20 2019
%Y A116301 Cf. A116170, A116294, A116302, A116307.
%K A116301 nonn,base
%O A116301 1,1
%A A116301 _Giovanni Resta_, Feb 06 2006