private static bool AnExplicitPairExists(int i)
{
int last = new IndexableNumber(i)[1];
var parts = new IndexableNumber(i).DigitsBase10().NotStupidSplit(x =>
{
// split on change
bool flag = x != last;
last = x;
return(flag);
});
var distinctParts = parts.DistinctBy(p => p.Aggregate(0, (acc, curr) => acc * 497 + curr));
return(distinctParts.Any(p => p.Count() == 2));
}
