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.

A331464 Numbers k such that k and k + 1 are both binary Smith numbers (A278909).

This page as a plain text file.
%I A331464 #10 Jan 18 2020 03:12:08
%S A331464 1369,1370,1390,1630,1929,2525,2526,2930,3013,3309,3501,3502,3686,
%T A331464 3805,3953,3954,4043,4726,4854,5620,5621,5917,6068,6682,6774,6838,
%U A331464 7025,7089,7115,7671,7738,7786,8075,9654,9915,10366,10982,11166,11227,11506,11673,11740,11763
%N A331464 Numbers k such that k and k + 1 are both binary Smith numbers (A278909).
%H A331464 Amiram Eldar, <a href="/A331464/b331464.txt">Table of n, a(n) for n = 1..10000</a>
%e A331464 1369 is in the sequence since both 1369 and 1369 + 1 = 1370 are binary Smith numbers.
%t A331464 binWt[n_] := Total @ IntegerDigits[n, 2]; binSmithQ[n_] := CompositeQ[n] && Plus @@ (Last@# * binWt[ First@# ] & /@ FactorInteger[n]) == binWt[n]; seq = {}; isSmith1 = binSmithQ[1]; Do[isSmith2 = binSmithQ[n]; If[isSmith1 && isSmith2, AppendTo[seq, n-1]]; isSmith1 = isSmith2, {n, 2, 12000}]; seq
%Y A331464 Cf. A006753, A050219, A050220, A278909, A331463, A331465.
%K A331464 nonn,base
%O A331464 1,1
%A A331464 _Amiram Eldar_, Jan 17 2020