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 A076667 antisigma(n) + antisigma(n+3) = antisigma(n+1) + antisigma(n+2), where antisigma(n) = sum of the non-divisors of n that are between 1 and n. 0
 6, 907, 1359, 2512, 26545, 6094105, 10714840, 11967486, 36282316, 45123265, 60144196, 113547460, 318424060, 474656416, 488176150, 920250976, 927186976, 993590680, 2509123036, 3015854296, 3966424141, 4168017460, 4360145356 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Each term of the sequence marks the start of four consecutive antisigma-values for which the sum of the means equals the sum of the extremes. LINKS EXAMPLE antisigma(6) + antisigma(9) = 9 + 32 = 41; antisigma(7) + antisigma(8) = 20 + 21 = 41, so 6 is a term of the sequence. MATHEMATICA antisigma[n_] := (n (n + 1) / 2) - DivisorSigma[1, n]; Select[Range[10^5], antisigma[ # ] + antisigma[ # + 3] == antisigma[ # + 1] + antisigma[ # + 2] &] CROSSREFS Sequence in context: A180992 A229629 A137801 * A000652 A214638 A175554 Adjacent sequences:  A076664 A076665 A076666 * A076668 A076669 A076670 KEYWORD nonn AUTHOR Joseph L. Pe, Oct 25 2002 EXTENSIONS a(6)-a(23) from Donovan Johnson, Dec 02 2009 STATUS approved

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Last modified December 5 03:31 EST 2020. Contains 338943 sequences. (Running on oeis4.)