Searching many formulas to one limit
Hi guys!
This is formula for nth rgonal pyramidal number [TEX]P_n^r= \frac{3n^2 + n^3(r2)  n(r5)}{6}[/TEX] I have , for example 2<r<1000. And i want to search all this numbers to one constant border(for example 10[SUP]15[/SUP]) How i can find such n's in C++? Prethanks 
And i forget about searching from some minimal border.
How to find n[SUB]min[/SUB] without computing previous [TEX]P_n^r[/TEX]? Prethx 
What exactly are you searching for?

Im searching for numbers that ngonal pyramidal number and nangular number. Cannonball problem for different bases

[QUOTE=vasyannyasha;520023]Im searching for numbers that ngonal pyramidal number and nangular number. Cannonball problem for different bases[/QUOTE]
For a given r, an rgonal number is of the form [tex]p_r^{n} \;=\; n((r2)*n(r4))/2[/tex] Multiplying by 1/2*(r  2) and adding 1/16*r^2  1/2*r + 1 gives a square y^2. (Note that when r = 4 you multiply by 1 and add 0). Thus, for a given r you can write [tex](r  2)P_r^{n}/2 \; + \; \frac{r^{2}}{16}\;\;\frac{r}{2}\;+\;1\;=\;y^{2}[/tex] where the P is the n[sup]th[/sup] rpyramidal number, which is cubic in n. For any given r, this is an elliptic curve. This gives a mighty bludgeon to use on the problem. For r = 4, there are elementary proofs that n = 70 is the only n > 1 giving a square value for the cannonball problem. 
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