The first Strehl identity is the binomial sum identity sum_(k = 0)^n (n k)^3 = sum_(k = 0)^n (n k)^2(2k n), (Strehl 1993, 1994; Koepf 1998, p. 55), which are the so-called Franel numbers. For n = 1, 2, ..., the first few terms are 1, 2, 10, 56, 346, 2252, 15184, 104960, ... (OEIS A000172).

Apéry number | binomial coefficient | binomial sums | Franel number | Schmidt's problem