cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A373347 Positive integers k such that A000120(k) > A001511(k).

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%I A373347 #32 Aug 12 2025 14:46:46
%S A373347 3,5,7,9,11,13,14,15,17,19,21,22,23,25,26,27,29,30,31,33,35,37,38,39,
%T A373347 41,42,43,45,46,47,49,50,51,53,54,55,57,58,59,60,61,62,63,65,67,69,70,
%U A373347 71,73,74,75,77,78,79,81,82,83,85,86,87,89,90,91,92,93,94,95,97,98,99
%N A373347 Positive integers k such that A000120(k) > A001511(k).
%C A373347 Numbers whose binary expansion does not encode for any Schreier set (cf. A371176 and A373345).
%C A373347 All odd numbers > 1 are terms.
%H A373347 Paolo Xausa, <a href="/A373347/b373347.txt">Table of n, a(n) for n = 1..10000</a>
%F A373347 a(k) = 2^(n+1) - 1; a(k+1) = 2^(n+1) + 1, where k = A008466(n+1).
%t A373347 Select[Range[100], DigitSum[#, 2] > IntegerExponent[#, 2] + 1 &]
%o A373347 (Python)
%o A373347 def isa(n): return (n - 1).bit_count() < ((n.bit_count() - 1) << 1)
%o A373347 print([n for n in range(100) if isa(n)])  # _Peter Luschny_, Jun 07 2024
%o A373347 (PARI) isok(k) = hammingweight(k) > valuation(2*k, 2); \\ _Michel Marcus_, Jun 07 2024
%Y A373347 Complement of A371176.
%Y A373347 Cf. A000120, A001511, A008466, A373345, A373360 (first differences).
%K A373347 nonn,easy,base
%O A373347 1,1
%A A373347 _Paolo Xausa_, Jun 01 2024