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%I #12 Dec 06 2016 22:05:03
%S 17,13,25,11,33,55,41,10,126,224,189,268,434,106,729,1539,981,315,
%T 1079,313,844,416,415,1178551,1373,309,1471,1575,721,1456,1667,1133,
%U 820,306,818,612,1961,305,2059,1224,406,1530,2255,1527,2353,2142,1217,1420,101,303
%N Least number k = concat(x,y) such that k = n*(x+y) - x * y , -1 if such a number does not exist.
%C a(10^k) = 10^k, for k>=1.
%C MSD of y can be 0.
%C In the first 1000 terms only 30060 is present two times, in a(354) and a(480).
%H Paolo P. Lava, <a href="/A279058/b279058.txt">Table of n, a(n) for n = 3..1000</a>
%e a(11) = 126 = concat(12,6) and 11*(12 + 6) - 12*6 = 126;
%e a(222) = 3921381 = concat(39,21381) and 222*(39 + 21381) - 39*21381 = 3921381.
%p with(numtheory): P:=proc(q) local j,k,s,t,n,ok;
%p for j from 3 to q do ok:=1; for n from 1 to q do if ok=0 then break; else
%p for k from 1 to ilog10(n) do s:=n mod 10^k; t:=trunc(n/10^k);
%p if j*(s+t)-s*t=n then print(n); ok:=0; break; fi; od; fi; od; od; end: P(10^6);
%Y Cf. A278935.
%K nonn,base
%O 3,1
%A _Paolo P. Lava_, Dec 05 2016
%E a(258) by _Giovanni Resta_, Dec 05 2016
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