A116268 Numbers k such that k*(k+5) gives the concatenation of two numbers m and m-3.

81, 77394227, 89158933, 36623663376237623663376335, 37633762366336633762366235, 62366237633663366237633761, 63376336623762376336623661, 86194223018927804587702128, 88063202723646452838040443, 35574229497606875609044578088011, 35693849662968953146129859753682, 42317841210726174031503123524229

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..220

Example

89158933 * 89158938 = 79493157//79493154, where // denotes concatenation.

Maple

f:= proc(d) local k, K;
      K:= map(t -> rhs(op(t)), [msolve(k^2+5*k+3=0, 10^d+1)]);
      op(sort(select(k -> k^2 + 5*k + 3 >= (10^d+1)*10^(d-1), K)));
end proc:
map(f, [$1..62]); # Robert Israel, Jul 10 2025

Crossrefs

Cf. A028557, A116099, A116261, A116267, A116269, A116276.

Sequence in context: A277844 A162284 A309110 * A128838 A231484 A340398

Adjacent sequences: A116265 A116266 A116267 * A116269 A116270 A116271

Keyword

nonn,base

Author

Giovanni Resta, Feb 06 2006

Extensions

More terms from Robert Israel, Jul 10 2025

Status

approved