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.

A255683 Sum of the binary numbers whose digits are cyclic permutations of the binary expansion of n.

Original entry on oeis.org

1, 3, 6, 7, 14, 14, 21, 15, 30, 30, 45, 30, 45, 45, 60, 31, 62, 62, 93, 62, 93, 93, 124, 62, 93, 93, 124, 93, 124, 124, 155, 63, 126, 126, 189, 126, 189, 189, 252, 126, 189, 189, 252, 189, 252, 252, 315, 126, 189, 189, 252, 189, 252, 252, 315, 189, 252, 252, 315
Offset: 1

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Author

Paolo P. Lava, Mar 02 2015

Keywords

Comments

All the primes in the sequence are Mersenne primes (A000668).

Examples

			6 in base 2 is 110 and all the cyclic permutations of its digits are: 110, 101, 011. In base 10 they are 6, 5, 3 and their sum is 6 + 5 + 3 = 14.
From _Peter Bala_, Mar 02 2015: (Start)
Let b(n) = A063787(n), beginning [1, 2, 2, 3, 2, 3, 3, 4, ...]. Then
[a(1)] = 1*[b(1)]; [a(2), a(3)] = 3*[b(1), b(2)];
[a(4), a(5), a(6), a(7)] = 7*[b(1), b(2), b(3), b(4)];
[a(8), a(9), a(10), a(11), a(12), a(13), a(14), a(15)] = 15*[b(1), b(2), b(3), b(4), b(5), b(6), b(7), b(8)].
It is conjectured that this relationship continues. (End)
		

Crossrefs

Programs

  • Maple
    with(numtheory): P:=proc(q) local a,b,c,k,n;
    for n from 1 to q do a:=convert(n,binary,decimal); b:=n; c:=ilog10(a);
    for k from 1 to c do a:=(a mod 10)*10^c+trunc(a/10); b:=b+convert(a,decimal,binary); od;
    print(b); od; end: P(1000);
  • Mathematica
    f[n_] := Block[{b = 2, w = IntegerDigits[n, b]}, Apply[Plus, FromDigits[#, b] & /@ (RotateRight[w, #] & /@ Range[Length@ w])]]; Array[f, 60] (* Michael De Vlieger, Mar 04 2015 *)
    Table[Total[FromDigits[#,2]&/@Table[RotateRight[IntegerDigits[k,2],n],{n,IntegerLength[k,2]}]],{k,60}] (* Harvey P. Dale, Jan 03 2018 *)

Formula

a(2^n) = Sum_{k=1..n} 2^k = 2^(n+1)-1.
a(5+4*k) = a(6+4*k), for k >= 0.
For n >= 0 and 0 <= i <= 2^n - 1 we conjecture a(2^n + i) = (2^(n+1) - 1)*A063787(i+1). An example is given below. - Peter Bala, Mar 02 2015
a(n) = A000120(n)*(A000918(A000523(n) + 1) + 1). - Alan Michael Gómez Calderón, Jul 07 2025