A168475 Primes of the form: sum of 3 consecutive products of two distinct primes.

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

Robert Israel, Table of n, a(n) for n = 1..10000

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

Cf. A006881, A168474

Sequence in context: A039555 A161403 A251145 * A142662 A178416 A182477

Adjacent sequences: A168472 A168473 A168474 * A168476 A168477 A168478

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Nov 26 2009

Status

approved