%I #32 Jan 02 2023 12:30:50
%S 0,1,3,8,12,36,24,60,36,84,156,60,204,156,84,180,300,336,120,384,276,
%T 144,456,324,516,744,396,204,420,216,444,1680,516,804,276,1440,300,
%U 924,960,660,1020,1056,360,1860,384,780,396,2460,2604,900,456,924,1416,480
%N Number of even numbers in classes of classification of the positive numbers defined in comment in A247395.
%C In the classification every class contains no more than a finite number of numbers with a given least prime divisor.
%H Indranil Ghosh, <a href="/A247396/b247396.txt">Table of n, a(n) for n = 0..1000</a>
%H Vladimir Shevelev, <a href="http://list.seqfan.eu/oldermail/seqfan/2014-September/013643.html">A classification of the positive integers over primes</a>
%F For n>=3, a(n) = (prime(n)^2 - prime(n-1)^2)/2.
%e a(6) = (prime(6)^2 - prime(5)^2)/2 = (13^2 - 11^2)/2 = 24. - _Indranil Ghosh_, Mar 08 2017
%p A247396:=n->(ithprime(n)^2 - ithprime(n-1)^2)/2: 0,1,3,seq(A247396(n), n=3..100); # _Wesley Ivan Hurt_, Apr 18 2017
%t a[0] = 0; a[1] = 1; a[2] = 3; a[n_] := (Prime[n]^2 - Prime[n - 1]^2) / 2; Table[a[n], {n, 0, 53}] (* _Indranil Ghosh_, Mar 08 2017 *)
%o (PARI) for(n=0, 53, print1(if(n>2, (prime(n)^2 - prime(n - 1)^2)/2, if(n<2, n, 3)),", ")) \\ _Indranil Ghosh_, Mar 08 2017
%Y Cf. A000040, A156759, A247393, A247394, A247395.
%K nonn
%O 0,3
%A _Vladimir Shevelev_, Sep 16 2014
%E More terms from _Peter J. C. Moses_, Sep 17 2014