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.

Showing 1-4 of 4 results.

A169810 a(n) = n XOR n^2.

Original entry on oeis.org

0, 0, 6, 10, 20, 28, 34, 54, 72, 88, 110, 114, 156, 164, 202, 238, 272, 304, 342, 378, 388, 428, 498, 518, 600, 616, 702, 706, 780, 852, 922, 990, 1056, 1120, 1190, 1258, 1332, 1404, 1410, 1494, 1640, 1720, 1742, 1810, 1980, 1988, 2154, 2190, 2352, 2384, 2550, 2586
Offset: 0

Views

Author

N. J. A. Sloane, May 28 2010

Keywords

Comments

XOR the binary representations of n and n^2.

Examples

			a(5) = 28:
..101 <- 5
11001 <- 25
----- <- XOR
11100 -> 28
		

Crossrefs

Suggested by A174375. Cf. A070883, A169811-A169814.
Cf. A007745 (OR), A213541 (AND), A002378.

Programs

  • Haskell
    import Data.Bits (xor)
    a169810 n = n ^ 2 `xor` n :: Integer
    -- Reinhard Zumkeller, Dec 27 2012
    
  • Maple
    f:=proc(n) local i,t0,t1,t2,ts,tl,n1,n2;
    t1:=convert(n,base,2); t2:=convert(n^2,base,2); n1:=nops(t1); n2:=nops(t2);
    if n1 < n2 then ts:= t1; tl:=t2; else ts:=t2; tl:=t1; fi;
    t0:=[]; for i from 1 to nops(ts) do t0:=[op(t0), (ts[i] + tl[i]) mod 2 ]; od:
    for i from nops(ts)+1 to nops(tl) do t0:=[op(t0), tl[i]]; od:
    add(2^(i-1)*t0[i], i=1..nops(t0)); end;
    # second Maple program:
    a:= n-> Bits[Xor](n, n^2):
    seq(a(n), n=0..100);  # Alois P. Heinz, Mar 29 2018
  • Mathematica
    a[n_]:=BitXor[n, n^2]; Array[a, 60, 0] (* Robert G. Wilson v, Jun 09 2010 *)
  • PARI
    A169810(n)=bitxor(n^2,n) \\ M. F. Hasler, May 07 2023
    
  • Python
    A169810=lambda n:n**2^n # M. F. Hasler, May 07 2023

A169813 a(n) = n XOR sigma(n), where sigma(n) is the number of divisors of n, A000203.

Original entry on oeis.org

0, 1, 7, 3, 3, 10, 15, 7, 4, 24, 7, 16, 3, 22, 23, 15, 3, 53, 7, 62, 53, 50, 15, 36, 6, 48, 51, 36, 3, 86, 63, 31, 17, 20, 19, 127, 3, 26, 31, 114, 3, 74, 7, 120, 99, 102, 31, 76, 8, 111, 123, 86, 3, 78, 127, 64, 105, 96, 7, 148, 3, 94, 87, 63, 21, 210, 7, 58, 37, 214, 15, 139, 3, 56
Offset: 1

Views

Author

N. J. A. Sloane, May 28 2010

Keywords

Crossrefs

Programs

A169812 a(n) = n XOR d(n) (cf. A000005).

Original entry on oeis.org

0, 0, 1, 7, 7, 2, 5, 12, 10, 14, 9, 10, 15, 10, 11, 21, 19, 20, 17, 18, 17, 18, 21, 16, 26, 30, 31, 26, 31, 22, 29, 38, 37, 38, 39, 45, 39, 34, 35, 32, 43, 34, 41, 42, 43, 42, 45, 58, 50, 52, 55, 50, 55, 62, 51, 48, 61, 62, 57, 48, 63, 58, 57, 71, 69, 74, 65, 66, 65, 78, 69, 68, 75, 78
Offset: 1

Views

Author

N. J. A. Sloane, May 28 2010

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_] := BitXor[n, DivisorSigma[0, n]]; Array[a, 100] (* Amiram Eldar, Jul 08 2019 *)
  • PARI
    a(n)=bitxor(n, numdiv(n)); \\ Michel Marcus, Jul 08 2019

A362951 a(n) is the Hamming distance between the binary expansions of n and phi(n) where phi is the Euler totient function (A000010).

Original entry on oeis.org

0, 2, 1, 2, 1, 1, 1, 2, 4, 3, 1, 1, 1, 1, 3, 2, 1, 2, 1, 3, 3, 3, 1, 1, 3, 3, 2, 1, 1, 3, 1, 2, 4, 3, 5, 2, 1, 3, 6, 3, 1, 3, 1, 3, 4, 3, 1, 1, 4, 3, 3, 3, 1, 2, 5, 1, 4, 3, 1, 3, 1, 1, 4, 2, 4, 4, 1, 3, 4, 5, 1, 2, 1, 5, 4, 3, 4, 4, 1, 3, 5, 5, 1, 3, 3, 5, 6
Offset: 1

Views

Author

DarĂ­o Clavijo, Jul 05 2023

Keywords

Comments

a(2^k) = 2 for k >= 1.
a(p) = 1 for each odd prime p because phi(p) = p-1 and (p-1 xor p) = 1.

Crossrefs

Programs

  • Mathematica
    A362951[n_] := DigitCount[BitXor[n, EulerPhi[n]], 2, 1];
    Array[A362951, 100] (* Paolo Xausa, Feb 20 2024 *)
  • Python
    from gmpy2 import mpz, hamdist
    from sympy import totient
    a = lambda n: hamdist(mpz(n), mpz(totient(n)))
    print([a(n) for n in range(1, 87)])
    
  • Python
    from sympy import totient
    def A362951(n): return (n^totient(n)).bit_count() # Chai Wah Wu, Jul 07 2023

Formula

a(n) = A101080(n,A000010(n)).
a(n) = A000120(A169814(n)).
Showing 1-4 of 4 results.