A177512 - OEIS

%I #16 Sep 15 2019 07:56:49

%S 1,2,5,7,11,13,17,19,23,25,29,31,37,41,43,47,49,53,59,61,67,71,73,79,

%T 83,89,97,101,103,107,109,113,121,127,131,137,139,149,151,157,163,167,

%U 169,173,179,181,191,193,197,199,211,223,227,229,233,239,241,251

%N A053735-deficient numbers.

%C For definition, see A175522.

%C All primes, except for 3, are in the sequence.

%C It also contains squared primes p^2 for p = 5, 7, 11, 13, 19, 23, 29, 31, 37.. (not matching current OEIS sequences). What characterizes these p?

%H Amiram Eldar, <a href="/A177512/b177512.txt">Table of n, a(n) for n = 1..10000</a>

%F {n: sum_{d|n, d<n} A053735(d) < A053735(n)}.

%o (Sage) is_A177512 = lambda n: sum(A053735(d) for d in divisors(n)) < 2*A053735(n) # _D. S. McNeil_, Dec 11 2010

%o (PARI) isok(n) = sumdiv(n, d, (d<n)* vecsum(digits(d,3))) < vecsum(digits(n, 3)); \\ _Michel Marcus_, Feb 06 2016

%Y Cf. A177511 (perfect version), A175524, A175811, A000040, A005100, A005101.

%K nonn,base

%O 1,2

%A _Vladimir Shevelev_, Dec 11 2010