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A067354 Numbers k such that prime(k+2)-(k+2)*tau(k+2) = prime(k-2)-(k-2)*tau(k-2) where tau(k) = A000005(k) is the number of divisors of k. 1
3, 8, 30, 68, 277, 600, 1444, 2123, 3128, 3230, 3672, 3783, 4441, 5016, 5052, 5144, 5304, 5665, 6353, 6468, 6513, 6588, 6772, 6983, 7044, 7087, 8392, 8418, 8632, 8866, 9217, 9264, 9292, 9540, 9917, 9949, 10495, 11429, 11532, 13474, 14063, 15431 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
MATHEMATICA
Select[Range[3, 16000], Prime[#-2]-(#-2)DivisorSigma[0, #-2]==Prime[#+2]-(#+2)DivisorSigma[0, #+2]&] (* Harvey P. Dale, Dec 20 2015 *)
PROG
(PARI) f(n) = prime(n) - n * numdiv(n);
is(n) = n > 2 && f(n-2) == f(n+2); \\ Amiram Eldar, Apr 16 2024
CROSSREFS
Sequence in context: A289486 A245361 A247340 * A344899 A148877 A148878
KEYWORD
easy,nonn
AUTHOR
Benoit Cloitre, Feb 24 2002
STATUS
approved

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Last modified June 20 07:26 EDT 2024. Contains 373512 sequences. (Running on oeis4.)