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A089268 Odd semiprimes m such that m-2 is composite. 3
35, 51, 57, 65, 77, 87, 93, 95, 119, 121, 123, 143, 145, 155, 161, 177, 185, 187, 203, 205, 209, 215, 217, 219, 221, 237, 247, 249, 267, 287, 289, 291, 299, 301, 303, 305, 321, 323, 327, 329, 335, 341, 365, 371, 377, 393, 395, 407, 413, 415, 417, 427, 437 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A087942(a(n)) = 0.

Assuming Goldbach's conjecture that every even number greater than 2 is the sum of two primes, these are the numbers that are the product of two primes but not the sum of two primes. - Michael B. Porter, Feb 08 2013

LINKS

Table of n, a(n) for n=1..53.

MATHEMATICA

Take[Select[Union[Flatten[Table[Prime[i] Prime[j], {i, 2, 25}, {j, 2, 25}]]], Not[PrimeQ[# - 2]] &], 50] (* Alonso del Arte, Feb 08 2013 *)

CROSSREFS

Cf. A062721, A046315, A001358.

Sequence in context: A249819 A186319 A248659 * A214469 A306117 A039418

Adjacent sequences:  A089265 A089266 A089267 * A089269 A089270 A089271

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Oct 28 2003

STATUS

approved

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Last modified January 23 13:34 EST 2020. Contains 331171 sequences. (Running on oeis4.)