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

computer exploration shows likely true -- no proof by Charlie)

Cn,

1. You somehow missed x=1 y=0; a valid triangular number

2. You were very close to proof, not verification- all you needed

was to assume a linear recurrence equation and to show that it assures divisibility by 28.

3.Please read my post and ,if needed, comment on it.