A074820 Numbers k such that mu(k) = mu(k+2), where mu is the Möbius function (A008683).

3, 5, 11, 16, 17, 18, 25, 29, 33, 41, 48, 50, 52, 54, 55, 59, 71, 85, 88, 90, 91, 93, 96, 98, 101, 103, 105, 107, 124, 126, 137, 141, 143, 148, 149, 150, 159, 160, 162, 163, 165, 169, 179, 183, 185, 191, 193, 195, 196, 197, 198, 201, 203, 213, 215, 217, 219, 227

Offset

1,1

Comments

a(n) seems to be asymptotic to c*n with c near 3.73. Probably c = 1/(3A/2 + 1 - 12/Pi^2) ~ 3.729994018, where A ~ 0.322634099 is the product over all primes p of 1 - 2/p^2.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Example

3 is a term since mu(3) = mu(5) = -1.

Mathematica

Select[Range[230], MoebiusMu[ # ]==MoebiusMu[ #+2]&]
Flatten[Position[Partition[MoebiusMu[Range[250]], 3, 1], _?(#[[1]]==#[[3]]&), {1}, Heads->False]] (* Harvey P. Dale, Mar 08 2015 *)

Crossrefs

Cf. A008683, A064148.

Sequence in context: A322439 A018313 A219039 * A327043 A006169 A323582

Adjacent sequences: A074817 A074818 A074819 * A074821 A074822 A074823

Keyword

nonn

Author

Benoit Cloitre, Sep 08 2002

Extensions

Edited by Dean Hickerson, Sep 10 2002

Status

approved