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.
%I A103680 #22 Apr 03 2025 02:54:16 %S A103680 7,8,100,113,117,123,136,145,155,156,163,165,168,179,186,203,245,247, %T A103680 248,259,265,275,283,289,293,294,296,305,307,309,311,318,328,330,341, %U A103680 342,343,346,352,355,360,375,384,386,399,402,405,408,410,413,415,419 %N A103680 Numbers m such that the binary representation of m! contains 7!. %C A103680 All the numbers from 5154 to 5*10^5 belong to the sequence. - _Giovanni Resta_, Apr 07 2013 %H A103680 Amiram Eldar, <a href="/A103680/b103680.txt">Table of n, a(n) for n = 1..10000</a> %H A103680 <a href="/index/Bi#binary">Index entries for sequences related to binary expansion of n</a>. %H A103680 <a href="/index/Fa#factorial">Index entries for sequences related to factorial numbers</a>. %F A103680 A103675(a(n)) = 1, A103675(A103681(n)) = 0. %t A103680 Select[Range[0, 420], StringContainsQ[IntegerString[#!, 2], IntegerString[7!, 2]] &] (* _Amiram Eldar_, Apr 03 2025 *) %o A103680 (PARI) is(n)=n=n!; while(n>5039, my(e=valuation(n, 2), e1=valuation((n>>=e)+1, 2)); n>>=e1; if(e>3 && e1==2 && bitand(n, 127)==78, return(1))); 0 \\ _Charles R Greathouse IV_, Apr 07 2013 %Y A103680 Complement of A103681. %Y A103680 Cf. A000142, A007088, A036603, A102730, A103676, A103678, A103679. %K A103680 base,nonn %O A103680 1,1 %A A103680 _Reinhard Zumkeller_, Feb 12 2005