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 A063981 Numbers n such that t(n) = sigma(n) - n, where t(n) = A008472(n+1) - A008472(n). 0

%I #8 Dec 15 2017 17:35:35

%S 2,4,9,16,81,85,256,931,65536,4599097,6309263,16905401,43046721,

%T 54116239,68229263,98643563,208288271,222933913,226461649,230893123,

%U 280399957,381001633,412016873,417814973,485674237,620336281,736284077

%N Numbers n such that t(n) = sigma(n) - n, where t(n) = A008472(n+1) - A008472(n).

%t a = 0; b = 0; Do[a = b; b = Apply[ Plus, Transpose[ FactorInteger[n + 1]] [[1]]]; If[ b - a == DivisorSigma[1, n] - n, Print[n]], {n, 1, 2*10^7} ]

%Y Cf. A008472, A001065.

%K nonn

%O 1,1

%A _Jason Earls_, Sep 05 2001

%E More terms from _Robert G. Wilson v_, Oct 05 2001

%E a(14)-a(27) from _Donovan Johnson_, Oct 13 2009

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Last modified June 12 12:06 EDT 2024. Contains 373331 sequences. (Running on oeis4.)