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 A052396 (+2)-sigma perfect numbers: numbers k such that (+2)sigma(k) = 2*k, where (+2)sigma(k) = A107758(k). 2
 2, 4, 8, 16, 32, 63, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, 34587, 65536, 131072, 262144, 524288, 1048576, 2097152, 4194304, 8388608, 16777216, 33554432, 67108864, 134217728, 170271801, 268435456, 536870912, 1073741824, 2147483648, 4294967296 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS 2^n is a term for all n>=1. - Amiram Eldar, Aug 26 2022 LINKS Table of n, a(n) for n=1..35. EXAMPLE Factorizations: even examples: 2, 2^2, 2^3, 2^4,...; odd examples: a(6) = 3^2*7, a(17) = 3^4*7*61, a(30) = 3^6*7*61*547. MATHEMATICA f[p_, e_] := 1 + (p^(e + 1) - 1)/(p - 1); s[n_] := Times @@ f @@@ FactorInteger[n]; s[1] = 1; Select[Range[5*10^6], s[#] == 2*# &] (* Amiram Eldar, Aug 26 2022 *) CROSSREFS Cf. A000079, A107758. Sequence in context: A283837 A111663 A054043 * A051040 A006261 A290987 Adjacent sequences: A052393 A052394 A052395 * A052397 A052398 A052399 KEYWORD nonn AUTHOR Yasutoshi Kohmoto Mar 13 2000 EXTENSIONS Corrected by Franklin T. Adams-Watters, Oct 25 2006 a(30) corrected and a(31)-a(35) added by Amiram Eldar, Aug 26 2022 STATUS approved

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Last modified August 5 17:32 EDT 2024. Contains 374953 sequences. (Running on oeis4.)