A140460 - OEIS

%I #8 Sep 21 2024 15:16:39

%S 2,3,7,11,17,23,29,37,41,47,53,59,65,71,79,83,89,95,101,107,113,125,

%T 131,137,149,155,163,167,173,179,191,197,211,215,223,227,233,239,247,

%U 251,257,263,269,277,281,293,305,311,317,331,335

%N a(0) = 2; thereafter a(n) = smallest integer not a multiple of an earlier terms nor a sum of two earlier terms.

%C Note that the first composite value is a(12) = 65 = 5 * 13, since 5 and 13 are first two primes sieved out of the sequence. Similarly, the second composite value is a(17) = 95 = 5 * 19, since 5 and 19 are first and third primes sieved out of the sequence. - _Jonathan Vos Post_, Jul 27 2008

%H Nathaniel Johnston, <a href="/A140460/b140460.txt">Table of n, a(n) for n = 0..10000</a>

%o (C) void sieve(){ const int first = 2; const int max = 10000; bool member[max]; for(int i = first; i < max; ++i){ member[i] = true; } for(int i = first; i < max; ++i){ if(member[i]){ for(int x = i + i; x < max; x += i){ member[x] = false; } for(int j = first; j < i; ++j){ if(member[j] && i + j < max){ member[i + j] = false; } } } } int num = 0; for(int i = first; i < max; ++i){ if(member[i]){ printf("%i, ", i); num += 1; } } printf(" num = %i ", num); }

%Y Cf. A000040, A002858, A008320, A054016, A075573, A085947.

%K easy,nonn

%O 0,1

%A Russell Y. Webb (r.webb(AT)elec.canterbury.ac.nz), Jul 22 2008