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Numbers k congruent to 1 or 5 mod 6, for which A348930(k) > k.
4

%I #11 Nov 04 2021 20:47:08

%S 7,13,19,25,31,37,43,61,67,73,79,91,97,103,109,121,127,133,139,151,

%T 157,163,175,181,193,199,211,217,223,229,241,247,259,271,277,283,289,

%U 301,307,313,325,331,337,343,349,367,373,379,397,403,409,421,427,433,439,457,463,469,475,481,487,499,511,523,529,541

%N Numbers k congruent to 1 or 5 mod 6, for which A348930(k) > k.

%C See comments in A348930.

%H <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>

%t s[n_] := n / 3^IntegerExponent[n, 3]; Select[Range[550], MemberQ[{1, 5}, Mod[#, 6]] && s[DivisorSigma[1, #]] > # &] (* _Amiram Eldar_, Nov 04 2021 *)

%o (PARI)

%o A038502(n) = (n/3^valuation(n, 3));

%o A348930(n) = A038502(sigma(n));

%o isA348932(n) = ((n%2)&&(n%3)&&(A348930(n)>n));

%Y Cf. A007310, A348930, A348931.

%Y Cf. also A348742, A348754.

%K nonn

%O 1,1

%A _Antti Karttunen_, Nov 04 2021