cp's OEIS Frontend

A238256 A060308 begins with one 2, one 3, one 5, two 7's, one 11, two 13's, i.e., d(n) = 1, 1, 1, 2, 1, 2, 1, 2, 3, 1,... times the primes (A000040). a(n) uses this distribution with noncomposites (A008578).

%I A238256 #45 Nov 30 2014 14:27:14
%S A238256 1,2,3,5,5,7,11,11,13,17,17,19,19,19,23,29,29,29,31,31,37,41,41,43,43,
%T A238256 43,47,47,47,53,59,59,59,61,61,67,71,71,71,73,73,79,79,79,83,83,83,83,
%U A238256 89,89,97,101,101,103,107,107,109,109,109,109,109,109,109
%N A238256 A060308 begins with one 2, one 3, one 5, two 7's, one 11, two 13's, i.e., d(n) = 1, 1, 1, 2, 1, 2, 1, 2, 3, 1,... times the primes (A000040). a(n) uses this distribution with noncomposites (A008578).
%H A238256 Paul Curtz, <a href="/A238256/b238256.txt">Table of n, a(n) for n = 1..63</a>
%F A238256 Conjecture: a(n) is the greatest noncomposite (A008578) dividing A238691(n-1).
%o A238256 (PARI) lista(nn) = {nn = nn\2; v = vector(nn, i, precprime(2*i)); vnc = concat(1, vector(nn, i, prime(i))); nv = vector(1, i, vnc[i]); ivnc = 1; for (i=2, #v, if (v[i] == v[i-1], nv = concat(nv, nv[#nv]), ivnc++; nv = concat(nv, vnc[ivnc]));); for (i=1, #nv, print1(nv[i], ", "));} \\ _Michel Marcus_, Mar 20 2014
%Y A238256 Cf. A224911.
%K A238256 nonn
%O A238256 1,2
%A A238256 _Paul Curtz_, Mar 10 2014