Generate equation from pattern

100 Views Asked by Bumbble Comm At 27 Mar 2026 - 6:15

What equation describes the growth pattern of this sequence:

P = 5,25,35,55,65,85,95...

Heres the diferences:

5 (20) 25 (10) 35 (20) 55 (10) 65 ...

I have tried the P = Ax + B but it doesn work since the slope varies from 20 to 10.

Thanks!!

There are 2 best solutions below

Bumbble Comm On 14 Apr 2015 - 1:30

I would say :

$$P_n=10(n+E(\frac{n+1}{2}))+5 $$

Where $E(x)$ is the greatest integer which is less or equal to $x$.

Bumbble Comm On 15 Apr 2015 - 2:55

I found this guys: $$a(n) = \frac52(-3+(-1)^n+6n)$$ Its on OEIS.org. ( OEIS A084957 - multiples of $5$ whose GCD with $6$ is $1$.)