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%I #9 Jul 19 2021 19:54:26
%S 150,186,324,376,666,2046,3000,82650,100384,466716,1322316,4049584,
%T 67820074,110003884,135734074,156502836,196043286,213017754,238849000,
%U 261405396,289940826,310507774,365294050,398891964,446667216
%N Numbers k such that k concatenated with k+4 gives the product of two numbers which differ by 3.
%C Also numbers k such that k concatenated with k+6 gives the product of two numbers which differ by 1.
%p cc:=proc(x,y) local s: s:=proc(m) nops(convert(m,base,10)) end: x*10^s(y)+y: end: a:=proc(n) if type(sqrt(9+4*cc(n,n+4)),integer) then n else fi end: seq(a(n),n=1..500000); # very slow; cc yields the concatenation of x and y; - _Emeric Deutsch_, May 05 2007
%Y Cf. A116112, A115428, A115429, A116316, A116199, A116172, A116329.
%K nonn,base
%O 1,1
%A _Giovanni Resta_, Feb 06 2006
%E Edited by _N. J. A. Sloane_, Apr 14 2007
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