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Numbers k such that k and k+1 are both nobly abundant numbers (A349758).
2

%I #11 Dec 06 2021 03:11:39

%S 735,819,1035,1196,1274,1275,1449,1665,1700,1924,1925,1952,1988,2204,

%T 2324,2331,2540,2655,2960,2975,3068,3195,3267,3324,3339,3380,3549,

%U 3555,3626,3717,4004,4059,4164,4220,4235,4256,4556,4563,4598,4599,4635,4655,4675,4719

%N Numbers k such that k and k+1 are both nobly abundant numbers (A349758).

%H Amiram Eldar, <a href="/A349870/b349870.txt">Table of n, a(n) for n = 1..10000</a>

%e 735 is a term since 735 and 736 are both nobly abundant numbers: A000005(735) = A000005(736) = 12, A000203(735) = 1368 and A000203(736) = 1512 are all abundant numbers.

%t abQ[n_] := DivisorSigma[1, n] > 2*n; nobAbQ[n_] := And @@ abQ /@ DivisorSigma[{0, 1}, n]; Select[Range[50000], nobAbQ[#] && nobAbQ[# + 1] &]

%Y Cf. A000005, A000203, A005101, A096399.

%Y Subsequence of A349758.

%K nonn

%O 1,1

%A _Amiram Eldar_, Dec 03 2021