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 A342922 Numbers k such that A342925(k) = k + 2*A003415(k). 7
 6, 28, 29, 496, 857, 1721, 8128, 164284, 6511664, 33550336, 400902412, 8589869056 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Question: Are all odd terms in A001359? Certainly any prime p such that A003415(p+1) = p + 2 satisfies the equation. See comments in A007850. LINKS Table of n, a(n) for n=1..12. Index entries for sequences where odd perfect numbers must occur, if they exist at all MATHEMATICA Select[Range[2*10^5], #3 == #1 + 2 #2 & @@ Prepend[Map[If[# < 2, 0, # Total[#2/#1 & @@@ FactorInteger[#]]] &, {#, DivisorSigma[1, #]}], #] &] (* Michael De Vlieger, Feb 25 2022 *) PROG (PARI) A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1])); A342925(n) = A003415(sigma(n)); isA342922(n) = (A342925(n)==(n+(2*A003415(n)))); CROSSREFS Cf. A000396 (subsequence), A001359, A003415, A007850. Cf. A203617, A342923, A342924, A342925. Sequence in context: A215896 A211679 A261868 * A357462 A105402 A362805 Adjacent sequences: A342919 A342920 A342921 * A342923 A342924 A342925 KEYWORD nonn,more AUTHOR Antti Karttunen, Apr 07 2021 EXTENSIONS Terms a(11) and a(12) from Antti Karttunen, Feb 25 2022 STATUS approved

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Last modified June 19 00:22 EDT 2024. Contains 373492 sequences. (Running on oeis4.)