Select integer x and triangular number y such that 8y=3x^4-2x^2-1.
Prove that y is divisible by 28 - or find a counter-example.
(In reply to re: SOLUTION +some add-ons
Mr Broll, Esq
It is implicit indeed, but passed unnoticed.
I liked this problem very much - it forced me to go down the memory lane all the way to Recursion Avenue..