A116170 Numbers k such that k concatenated with k+2 gives the product of two numbers which differ by 1.

590, 738, 830, 1080, 4508, 20660, 29754, 980300, 6694218, 49826988, 117738578, 131505858, 132231404, 176445054, 177285320, 247979808, 252028388, 335180054, 336337790, 404958680, 406231130, 431477468, 499519478

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..9000

Maple

As:= {}:
for m from 2 to 20 do
   acands:= map(t -> rhs(op(t)), [msolve(a*(a+1)=2, 10^m+1)]);
   bcands:= map(t -> t*(t+1) mod 10^m, acands);
   good:= select(t -> bcands[t]>=10^(m-1), [$1..nops(acands)]);
   As:= As union convert(bcands[good], set);
od: map(t -> t-2, sort(convert(As, list))); # Robert Israel, Aug 20 2019

Crossrefs

Cf. A116163, A116171, A116099, A116301.

Sequence in context: A203628 A204752 A320713 * A171724 A195894 A263555

Adjacent sequences: A116167 A116168 A116169 * A116171 A116172 A116173

Keyword

nonn,base

Author

Giovanni Resta, Feb 06 2006

Status

approved