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 A121307 Products of three terms from A003627. 1
 8, 20, 44, 50, 68, 92, 110, 116, 125, 164, 170, 188, 212, 230, 236, 242, 275, 284, 290, 332, 356, 374, 404, 410, 425, 428, 452, 470, 506, 524, 530, 548, 575, 578, 590, 596, 605, 638, 668, 692, 710, 716, 725, 764, 782, 788, 830, 890, 902, 908, 932, 935, 956 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS It would be incorrect to call these Eisenstein 3-almost primes. For the Eisenstein primes see A055664. - N. J. A. Sloane, Feb 06 2008. REFERENCES J. H. Conway and R. K. Guy, The Book of Numbers. New York: Springer-Verlag, pp. 220-223, 1996. Stan Wagon, "Eisenstein Primes," Section 9.8 in Mathematica in Action. New York: W. H. Freeman, pp. 319-323, 1991. LINKS Giovanni Resta, Table of n, a(n) for n = 1..10000 MATHEMATICA ok[n_] := Block[{f = FactorInteger@n}, Plus @@ Last /@ f == 3 && Max@ Mod[1 + First /@ f, 3] == 0]; Select[Range@ 1000, ok] (* Giovanni Resta, Jun 12 2016 *) PROG (PARI) list(lim)=my(v=List(), u=v, t); forprime(p=2, lim\4, if(p%3==2, listput(u, p))); for(i=1, #u, for(j=i, #u, if(u[i]*u[j]^2>lim, break); for(k=j, #u, t=u[i]*u[j]*u[k]; if(t>lim, break); listput(v, t)))); Set(v) \\ Charles R Greathouse IV, Jan 31 2017 (Python) from sympy import primerange from itertools import combinations_with_replacement as mc def aupto(limit): terms = [p for p in primerange(2, limit//4+1) if p%3 == 2] return sorted(set(a*b*c for a, b, c in mc(terms, 3) if a*b*c <= limit)) print(aupto(957)) # Michael S. Branicky, Aug 20 2021 CROSSREFS Cf. A003627, A014612, A112770. Sequence in context: A318071 A308904 A192753 * A338471 A086169 A273241 Adjacent sequences: A121304 A121305 A121306 * A121308 A121309 A121310 KEYWORD easy,nonn AUTHOR Jonathan Vos Post, Sep 05 2006 EXTENSIONS Definition corrected by N. J. A. Sloane, Feb 06 2008 a(37)-a(53) from Giovanni Resta, Jun 12 2016 STATUS approved

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Last modified May 30 07:21 EDT 2023. Contains 363045 sequences. (Running on oeis4.)