# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a126253 Showing 1-1 of 1 %I A126253 #10 Feb 10 2014 03:29:21 %S A126253 3,4,7,6,10,8,15,13,18,12,22,14,26,36,31,18,34,20,38,54,42,24,46,31, %T A126253 50,40,54,30,130,32,63,88,66,120,70,38,74,105,78,42,192,44,86,111,90, %U A126253 48,94,57,98,141,102,54,106,210,110,159,114,60,255,62,122,162 %N A126253 a(n) = n-th integer from among those positive integers which are each coprime to exactly one prime dividing n. %e A126253 The positive integers which are each coprime to exactly one prime dividing 12 form the sequence: 2,3,4,8,9,10,14,15,16,20,21,22,26,27,28... The 12th of these is 22; so a(12) = 22. %o A126253 (PARI) a(n) = {ok = 0; nb = 0; i = 1; pf = factor(n)[,1]; while(! ok, if (sum(j=1, #pf, gcd(i, pf[j]) == 1) == 1, nb++); if (nb == n, ok = 1, i++);); i;} \\ _Michel Marcus_, Feb 10 2014 %Y A126253 Cf. A125704, A128487. %K A126253 nonn %O A126253 2,1 %A A126253 _Leroy Quet_, Mar 08 2007 %E A126253 Offset corrected and more terms from _Michel Marcus_, Feb 10 2014 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE