A116324 Numbers k such that k * (k+5) gives the concatenation of two numbers m and m+5.

31, 65, 42754, 57242, 75424, 425073, 574923, 979529, 4301394, 5698602, 7028667, 4925000748, 5074999248, 7748266575, 8511881485, 8814851185, 7059602159673, 7106167933829, 7439286611622, 7485852385778, 46791112884926

Offset: 1

Author

Giovanni Resta, Feb 06 2006

Keywords

• nonn
• base

Links

• Robert Israel, Table of n, a(n) for n = 1..5283

Crossrefs

Cf. A028557, A032610.

Cf. A116193, A116310, A116323, A116325, A116331.

Programs

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