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 A073500 Numbers n such that sigma(n) = sigma(n+1)+sigma(n-1). 6
 954, 1300, 11142, 38214, 89484, 152154, 167784, 254136, 303280, 473316, 574716, 813920, 918080, 1307022, 2008360, 3676242, 9878244, 10368512, 12548754, 19411480, 22493262, 42413484, 77766486, 81513816, 157874000, 240828972 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Donovan Johnson and Giovanni Resta, Table of n, a(n) for n = 1..170 (terms < 10^13, first 50 terms from Donovan Johnson) FORMULA a(n) = A076528(n)-1  - Alex Ratushnyak, Jul 06 2013. MAPLE with(numtheory); A073500:=proc(i) local n; for n from 1 to i do if sigma(n)=sigma(n+1)+sigma(n-1) then print(n); fi; od; end: A073500 (10^9); # Paolo P. Lava, Apr 24 2013 MATHEMATICA s1 = s2 = s3 = 0; Do[ s1 = s2; s2 = s3; s3 = DivisorSigma[1, n]; If[ s2 == s1 + s3, Print[n - 1]], {n, 1, 10^8}] CROSSREFS Cf. A000203, A076528. Sequence in context: A096954 A048267 A251677 * A121969 A203024 A055161 Adjacent sequences:  A073497 A073498 A073499 * A073501 A073502 A073503 KEYWORD nonn AUTHOR Benoit Cloitre, Aug 27 2002 EXTENSIONS Edited and extended by Robert G. Wilson v, Oct 24 2002 a(25)-a(26) from Donovan Johnson, Feb 01 2009 STATUS approved

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