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A177223 Numbers k that are the products of two distinct primes such that 2*k+1, 4*k+3 and 8*k+7 are also products of two distinct primes. 0
145, 203, 291, 298, 407, 497, 649, 707, 758, 815, 899, 926, 959, 995, 1079, 1094, 1139, 1142, 1157, 1313, 1403, 1415, 1461, 1497, 1538, 1639, 1658, 1691, 1857, 1934, 1945, 1991, 2123, 2159, 2217, 2234, 2315, 2603, 2629, 2807, 2991, 3215, 3254, 3279, 3305 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..45.

EXAMPLE

145 is a term because 145 = 5*29, 2*145 + 1 = 291 = 3*97, 4*145 + 1 = 583 = 11*53, and 8*145 + 1 = 1167 = 3*389.

MATHEMATICA

f[n_]:=Last/@FactorInteger[n]=={1, 1}; lst={}; Do[If[f[n]&&f[2*n+1]&&f[4*n+3]&&f[8*n+7], AppendTo[lst, n]], {n, 0, 2*7!}]; lst

CROSSREFS

Cf. A006881, A111153, A177210, A177211, A177212, A177213, A177214, A177215, A177216, A177217, A177220, A177221, A177222.

Sequence in context: A326258 A051414 A176699 * A318530 A158133 A094613

Adjacent sequences:  A177220 A177221 A177222 * A177224 A177225 A177226

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, May 05 2010

STATUS

approved

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Last modified April 22 14:20 EDT 2021. Contains 343177 sequences. (Running on oeis4.)