

A123093


Numbers which are not the sum of two 3almost primes.


0



1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 18, 19, 21, 22, 23, 25, 27, 29, 31, 33, 34, 37, 41, 43, 44, 49, 51, 59, 61, 66, 67, 85, 99, 101, 109, 163
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,2


COMMENTS

3almost prime analog of A072966, numbers which are not the sum of two semiprimes. In general, it seems that almost all even numbers can be written as the sum of two kalmost primes for any positive integer k.  T. D. Noe, Nov 06 2006


LINKS

Table of n, a(n) for n=1..42.


FORMULA

Complement of Sumset {A014612} + {A014612}.


MATHEMATICA

nn=10000; t3=Select[Range[2, nn], Plus@@Last/@FactorInteger[ # ]==3&]; t3sum=Table[0, {nn}]; Do[n=t3[[i]]+t3[[j]]; If[n<=nn, t3sum[[n]]=1], {i, Length[t3]}, {j, i, Length[t3]}]; Flatten[Position[t3sum, 0]] (* T. D. Noe, Nov 06 2006 *)


CROSSREFS

Cf. A014612.
Sequence in context: A337379 A121684 A191853 * A191932 A044920 A330938
Adjacent sequences: A123090 A123091 A123092 * A123094 A123095 A123096


KEYWORD

easy,fini,full,nonn


AUTHOR

Jonathan Vos Post, Sep 27 2006


EXTENSIONS

Edited by T. D. Noe, Nov 06 2006


STATUS

approved



