A few months ago, I came up with this conjecture that I am going to post today. This conjecture may seem elementary but I assure you it is a very difficult question to resolve. It goes like this.
x^a + x^b + x^c is divisible by 12, for all positive even integer values of (x, a, b, c) > 0.
I have not found a way to prove it formally. But I have tested it for various combinations of values for x, a, b and c. Here is an interactive excel sheet where you can test it out yourself.
https://numeracy.car.blog/wp-content/uploads/2019/07/akash-conjecture-01a-1.xlsx
The worksheet has a column and a row of random even integers. The random even integer greater than zero is generated with the formula =INT(RAND()$B$1)2+2
Cell B1 is the multiplier for the column of random numbers and Cell B2 is the multiplier for the row.
You can plug different values for A (cell B1) and B (Cell B2).
Each cell in the evaluated area calculates B$3^$A4+B$3^$A5+B$3^$A6)/12
In order to check if the division results in an integer, this formula is further enhanced to =IF((B$3^$A4+B$3^$A5+B$3^$A6)/12=INT((B$3^$A4+B$3^$A5+B$3^$A6)/12),1,0), so that the final result in the cell is a 1 or 0. A ‘1’ indicates that the conjecture is true for those set of values. Unfortunately, Excel’s capabilities to handle large numbers are limited. These are the times when you would find #NUM!, instead of ‘1’ (0r ‘0’; although I have never come across a ‘0’ so far). In such cases, I have verified it with a TI Nspire CX. You may want to do the same.
Instead of this elementary ad-hoc method of verification, I welcome the readers to provide a more generic proof. Although it sounds trivial, it does not appear so.
My sincere thanks to my grandfather, for helping me out with the Excel sheet.