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A001747
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2 together with primes multiplied by 2.
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39
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2, 4, 6, 10, 14, 22, 26, 34, 38, 46, 58, 62, 74, 82, 86, 94, 106, 118, 122, 134, 142, 146, 158, 166, 178, 194, 202, 206, 214, 218, 226, 254, 262, 274, 278, 298, 302, 314, 326, 334, 346, 358, 362, 382, 386, 394, 398, 422, 446, 454, 458, 466, 478, 482, 502
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OFFSET
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1,1
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COMMENTS
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When supplemented with 8, may be considered the "even primes", since these are the even numbers n = 2k which are divisible just by 1, 2, k and 2k. - Louis Zuckerman (louis(AT)trapezoid.com), Sep 12 2000
Sequence gives solutions of sigma(n) - phi(n) = n + tau(n) where tau(n) is the number of divisors of n.
Numbers n such that sigma(n) = 3*(n - phi(n)).
Except for 2, orders of non-cyclic groups k (in A060679(n)) such that x^k==1 (mod k) has only 1 solution 2<=x<=k. - Benoit Cloitre, May 10 2002
Together with 8 and 16, even numbers n such that n^2 does not divide (n/2)!. - Arkadiusz Wesolowski, Jul 16 2011
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LINKS
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FORMULA
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MATHEMATICA
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PROG
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(Magma) [2] cat [2*NthPrime(n): n in [1..60]]; // G. C. Greubel, May 18 2019
(Sage) [2]+[2*nth_prime(n) for n in (1..60)] # G. C. Greubel, May 18 2019
(GAP) Concatenation([2], List([1..60], n-> 2*Primes[n])) # G. C. Greubel, May 18 2019
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CROSSREFS
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KEYWORD
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nonn,easy,nice
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AUTHOR
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STATUS
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approved
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