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 A287653 Prime numbers of the form p*q + q*r + r*s with p,q,r,s consecutive primes. 3
 127, 1427, 2003, 2713, 7639, 76519, 81703, 139663, 166643, 173777, 349589, 371027, 653357, 696083, 752033, 793699, 883549, 938617, 974713, 1150733, 1176983, 1207223, 1310779, 1675577, 1702577, 1880363, 2715169 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Robert Israel, Table of n, a(n) for n = 1..10000 EXAMPLE a(1) = 127 = 3*5 + 5*7 + 7*11 = A000040(2)*A000040(3) + A000040(3)*A000040(4) + A000040(4)*A000040(5) = A006094(2) + A006094(3) + A006094(4). MAPLE N:= 100: # to get a(1) - a(N) p:= 2: q:= 3: r:= 5: s:= 7: count:= 0: while count < N do   p:= q; q:= r; r:= s; s:= nextprime(s);   n:= p*q+q*r+r*s;   if isprime(n) then count:= count+1; A[count]:= n fi od: seq(A[i], i=1..N); # Robert Israel, May 29 2017 PROG (PARI) {p=2; q=3; r=5; s=7; for(k=1, 1000, if(isprime(a=p*q+q*r+r*s), print1(a", ")); p=q; q=r; r=s; s=nextprime(1+s))} (Python) from sympy import nextprime, isprime A287653_list, pq, qr, rs, s = [], 6, 15, 35, 7 while s <= 10**6:     n = pq+qr+rs     if isprime(n):         A287653_list.append(n)     t = nextprime(s)     pq, qr, rs, s = qr, rs, s*t, t # Chai Wah Wu, May 29 2017 CROSSREFS Cf. A000040 (prime numbers), A006094 (products of 2 successive primes). Sequence in context: A299718 A300339 A189026 * A258012 A258002 A025598 Adjacent sequences:  A287650 A287651 A287652 * A287654 A287655 A287656 KEYWORD nonn AUTHOR Zak Seidov, May 29 2017 STATUS approved

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Last modified May 27 16:48 EDT 2022. Contains 354110 sequences. (Running on oeis4.)