OFFSET
1,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..200
Chun-Gang Ji, A simple proof of a curious congruence by Zhao, Proc. Amer. Math. Soc. 133 (2005).
FORMULA
Sum of binomial(prime(n), i)*binomial(prime(n), j)*binomial(prime(n), k) where i+j+k = prime(n) and i,j,k > 0 (see combinatorial identity on page 3471 in Chun-Gang Ji's paper).
MATHEMATICA
Table[Binomial[3 Prime[n], Prime[n]] - 3 Binomial[2 Prime[n], Prime[n]] + 3, {n, 20}]
Binomial[3#, #]-3Binomial[2#, #]+3&/@Prime[Range[20]] (* Harvey P. Dale, Jul 29 2021 *)
PROG
(Magma) [Binomial(3*p, p)-3*Binomial(2*p, p)+3: p in PrimesUpTo(50)];
(PARI) lista(nn) = {forprime(p=2, nn, print1(binomial(3*p, p) - 3*binomial(2*p, p) + 3, ", ")); } \\ Altug Alkan, May 05 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Vincenzo Librandi, May 05 2016
STATUS
approved