A226734 - OEIS

%I #12 May 09 2021 11:17:37

%S 0,0,0,0,0,0,14,30,15,0,0,0,0,0,90,34,102,57,0,0,0,0,138,210,195,156,

%T 84,0,0,0,434,198,0,0,420,222,0,0,390,410,0,0,0,330,345,0,846,546,560,

%U 765,0,0,159,165,770,798,0,0,0,0,0,1302,798,1170,0,0,0,0,0,0,2130

%N A002110(n) mod A000217(n).

%e a(7) = (2*3*5*7*11*13*17) mod triangular(7) = 510510 mod (7*8/2) = 14.

%p A226734 := proc(n)

%p     mul(ithprime(i),i=1..n) mod ( n*(n+1)/2) ;

%p end proc: # _R. J. Mathar_, Jun 18 2013

%o (Python)

%o primes = []

%o n = 2

%o primorial = 6

%o def addPrime(k):

%o   global n, primorial

%o   for p in primes:

%o     if k%p==0:  return

%o     if p*p > k:  break

%o   primes.append(k)

%o   print(primorial % (n*(n+1)/2), end=',')

%o   primorial *= k

%o   n += 1

%o print(0, end=',')  # 2 % 1

%o for p in range(5, 1000, 6):

%o   addPrime(p)

%o   addPrime(p+2)

%Y Cf. A002110, A000217.

%K nonn

%O 1,7

%A _Alex Ratushnyak_, Jun 15 2013