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A227854 Loeschian 3-almost primes: numbers with exactly three prime factors (with multiplicity) and of the form x^2 + x*y + y^2. 1
12, 27, 28, 52, 63, 75, 76, 117, 124, 147, 148, 171, 172, 175, 244, 268, 273, 279, 292, 316, 325, 333, 343, 363, 387, 388, 399, 412, 436, 475, 507, 508, 549, 556, 603, 604, 628, 637, 651, 652, 657, 711, 724, 741, 772, 775, 777, 796, 844, 847, 867, 873, 892 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

This is to A014612 as A230834 is to A001358.

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

FORMULA

A003136 INTERSECTION A014612.

EXAMPLE

a(1) = 12 = 2^2 * 3 = 2^2 + 2*2 + 2^2 (x = y = 2).

PROG

(PARI) list(lim)=my(v=List(), y, t); for(x=1, sqrtint(lim\3), my(y=x, t); while((t=x^2+x*y+y^2)<=lim, if(bigomega(t)==3, listput(v, t)); y++)); Set(v) \\ Charles R Greathouse IV, Feb 05 2017

CROSSREFS

Cf. A003136, A014612, A230834.

Sequence in context: A232936 A274897 A030736 * A003346 A047723 A151542

Adjacent sequences:  A227851 A227852 A227853 * A227855 A227856 A227857

KEYWORD

nonn,easy

AUTHOR

Jonathan Vos Post, Oct 31 2013

EXTENSIONS

More terms from Michel Marcus, Nov 08 2013

STATUS

approved

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Last modified March 22 10:07 EDT 2019. Contains 321421 sequences. (Running on oeis4.)