[seqfan] Sophie Germain pentagonal numbers

[Jonathan Post]

The pentagonal number analogue of
A124174  	 Sophie Germain triangular numbers tr: 2*tr+1 is also a
triangular number.

2*(A000326(j))+1 = A000326(k)

begins (denoting P(n) = n-th pentagonal number):
2P(0)+1 = 2*0+1 = 1 = P(1)
2P(75)+1 = 2*8400+1 = 16801 = P(106).

What are the next such values, which seem to be obtainable through a
Pell's equation?