Under 10^8, it looks as if all n >= 0 not of the form a^2+b^3+c^4+d^5 for a,b,c,d >= 0 are 15 23 55 62 71 471 478 510 646 806 839 879 939 1023 1063 1287 2127 5135 6811 7499 9191 26471 which one would surmise is a finite list. all n <= 10^8 appear to be of the form a^2+b^3+c^4+d^5+e^6 -------------------------------- - David Wilson