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.

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A265334 Numbers that are >= k! but < 2*k! for some k; numbers whose factorial base representation (A007623) begins with digit "1".

Original entry on oeis.org

1, 2, 3, 6, 7, 8, 9, 10, 11, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150
Offset: 1

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Author

Antti Karttunen, Dec 25 2015

Keywords

Comments

Numbers k for which A099563(k) = 1.
Numbers k for which A265333(k) = 1.

Examples

			1 is present as 1 >= 1! but < 2*1!
2 is present as 2 >= 2! but < 2*2!
3 is present as 3 >= 2! but < 2*2!
4 is not present as 4 >= 2! but not < 2*2! (and not >= 3!).
		

Crossrefs

Cf. A007623, A099563, A265333 (characteristic function).
Cf. A059590, A060112 (subsequences).
Cf. also A265897, A265898.

A014489 Positions of involutions (permutations whose square is the identity) in reverse colexicographic order (A055089/A195663).

Original entry on oeis.org

0, 1, 2, 5, 6, 7, 14, 16, 21, 23, 24, 25, 26, 29, 54, 55, 60, 67, 80, 82, 86, 94, 105, 107, 111, 119, 120, 121, 122, 125, 126, 127, 134, 136, 141, 143, 264, 265, 266, 269, 288, 289, 314, 316, 339, 341, 390, 391, 396, 403, 414, 415, 444, 450, 469
Offset: 0

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Author

Keywords

Crossrefs

Positions of zeros in A261099.
From a(1)=1 onward also positions of 2's in A055092.
Subsequences: A060112, A064640.
Cf. also A261220.

Programs

  • Maple
    N:= 100: # to get a(0) to a(N)
    M:= 0: A[0]:= 0: count:= 0:
    for m from 2 while count < N do
      P:= remove(t -> t[1]=1, combinat:-permute(m));
      P:= map(t -> ListTools:-Reverse(subs([seq(i=m+1-i,i=1..m)],t)),P);
      R:= select(t -> max(map(nops,convert(P[t],disjcyc))) = 2, [$1..nops(P)]);
      for r in R do
         count:= count+1;
         A[count]:= r+M;
         if count = N then break fi;
      od:
      M:= M + nops(P);
    od:
    seq(A[i],i=0..count); # Robert Israel, Oct 28 2015

Extensions

Name changed by Antti Karttunen, Aug 30 2015
Previous Showing 11-12 of 12 results.