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A168475
Primes of the form: sum of 3 consecutive products of two distinct primes.
1
107, 163, 233, 271, 359, 521, 719, 733, 839, 1129, 1187, 1231, 1693, 1733, 1777, 1847, 1871, 2053, 2137, 2287, 2423, 2543, 2593, 2677, 2719, 2843, 2897, 3217, 3229, 3257, 3491, 3623, 3659, 3853, 4019, 4027, 4219, 4231, 4243, 4441, 4591, 4679, 4751, 4903
OFFSET
1,1
LINKS
EXAMPLE
34 + 35 + 38 = 107, 51 + 55 + 57 = 163,..
MAPLE
N:= 5000: # to get terms where the three consecutive terms all < N
Primes:= select(isprime, [2, seq(2*k+1, k=1..floor(N/2))]):
L:= sort(convert({seq(seq(p*q, q=Primes[1..ListTools:-BinaryPlace(Primes, N/p)]), p=Primes)} minus {seq(p^2, p=Primes)}, list)):
select(isprime, [seq(L[i]+L[i+1]+L[i+2], i=1..nops(L)-2)]); # Robert Israel, Apr 29 2018
MATHEMATICA
f[n_]:=Last/@FactorInteger[n]=={1, 1}; a=6; b=10; lst={}; Do[If[f[n], p=a+b+n; If[PrimeQ[p], AppendTo[lst, p]]; a=b; b=n], {n, 13, 7!}]; lst
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved