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A328240
Numbers k such that the second arithmetic derivative of A276086(k) is prime.
8
4, 12, 32, 35, 40, 46, 47, 65, 67, 68, 71, 73, 74, 76, 220, 221, 225, 226, 227, 250, 256, 257, 276, 283, 284, 420, 421, 425, 426, 436, 486, 489, 494, 2324, 2325, 2352, 2370, 2387, 2525, 2530, 2531, 2555, 2560, 2565, 2566, 2583, 2596, 2734, 2739, 2760, 2765, 2769, 2771, 2773, 2795, 2797, 2798, 2803, 4623, 4627, 4628
OFFSET
1,1
COMMENTS
Numbers k for which A003415(A327860(k)) = A003415(A003415(A276086(k))) is a prime.
Numbers k such that A276086(k) is in A192192, or equally, k such that A327860(k) is in A157037.
FORMULA
For all n, a(A327969(n)) <= 5.
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); };
isA328240(n) = isprime(A003415(A327860(n)));
CROSSREFS
Subsequence of A328116 and of A328242.
Sequence in context: A171844 A324971 A273387 * A369817 A161217 A152527
KEYWORD
nonn
AUTHOR
Antti Karttunen, Oct 10 2019
STATUS
approved