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A116324
Numbers k such that k * (k+5) gives the concatenation of two numbers m and m+5.
6
31, 65, 42754, 57242, 75424, 425073, 574923, 979529, 4301394, 5698602, 7028667, 4925000748, 5074999248, 7748266575, 8511881485, 8814851185, 7059602159673, 7106167933829, 7439286611622, 7485852385778, 46791112884926
OFFSET
1,1
LINKS
MAPLE
f:= proc(d) local S, R, r, s, m, n;
r:= 10^d+1;
S:= map(t -> rhs(op(t)), [msolve(n*(n+5)=5, r)]);
S:= select(proc(s) local t; t:= (s*(s+5)-5)/r; t+5 >= (r-1)/10 and t+5 < r-1 end proc, S);
op(sort(S));
end proc:
map(f, [$1..20]); # Robert Israel, Jun 21 2024
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Giovanni Resta, Feb 06 2006
STATUS
approved