A300097 - OEIS

%I #14 Feb 27 2018 05:31:08

%S 5,7,11,17,23,29,37,53,59,67,79,89,97,127,191,211,223,307,331,479,521,

%T 541,809,877,907,1087,1277,1361,1931,2179,2203,2999,3299,4201,4327,

%U 4861,5779,7993,8923,12889,14143,15859,16411,16603,18839,19661,24317,25523,28277

%N Primes for which A288814 gives a new record.

%C These are the primes that require the most effort when searching for the least composite c such that A001414(c) is a given prime, where A001414 is sopfr (sum of prime factors with repetition).

%C From _David James Sycamore_, Feb 25 2018: (Start)

%C Also primes for which A295185 gives a new record.

%C A006512 gives primes p requiring least effort, since then c=2*(p-2). (End)

%o (PARI) isok(k, n) = my(f=factor(k)); sum(j=1, #f~, f[j, 1]*f[j, 2]) == n;

%o scompo(n) = forcomposite(k=4, ,if (isok(k, n), return(k)));

%o lista(nn) = {my(last = 0); forprime(p=4, nn, my(val = scompo(p)); if (val > last, print1(p, ", "); last = val););}

%Y Cf. A001414, A006512, A288814, A295185, A300098.

%K nonn

%O 1,1

%A _Michel Marcus_, Feb 24 2018