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 A328249 Numbers n such that the third arithmetic derivative of A276086(n) is prime. 2
 5, 15, 21, 31, 43, 79, 91, 98, 104, 106, 223, 229, 231, 254, 255, 289, 291, 301, 305, 423, 453, 456, 487, 670, 674, 677, 692, 702, 730, 736, 2343, 2378, 2380, 2400, 2409, 2534, 2537, 2543, 2552, 2562, 2585, 2602, 2618, 2629, 2767, 2804, 2821, 2831, 2839, 2942, 2943, 2957, 2962, 2963, 2974, 4621, 4669, 4672, 4687, 4717, 4841, 4844 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers n such that A003415(A003415(A327860(n))) = A099306(A276086(n)) is a prime. Numbers n such that A276086(n) is in A328239. For all n, A327969(a(n)) <= 6. This is sharp for example with a(7) = 91. LINKS Antti Karttunen, Table of n, a(n) for n = 1..1315 PROG (PARI) A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1])); A327860(n) = { my(m=1, i=0, s=0, pr=1, nextpr); while((n>0), i=i+1; nextpr = prime(i)*pr; if((n%nextpr), my(e=((n%nextpr)/pr)); m *= (prime(i)^e); s += (e / prime(i)); n-=(n%nextpr)); pr=nextpr); (s*m); }; isA328249(n) = isprime(A003415(A003415(A327860(n)))); CROSSREFS Cf. A003415, A099306, A276086, A327860, A327969, A328239, A328233, A328240. Sequence in context: A271576 A274535 A027184 * A110702 A141394 A127256 Adjacent sequences:  A328246 A328247 A328248 * A328250 A328251 A328252 KEYWORD nonn AUTHOR Antti Karttunen, Oct 11 2019 STATUS approved

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Last modified September 27 03:21 EDT 2020. Contains 337380 sequences. (Running on oeis4.)