login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A056189 a(n) = 2^n - A056188(n). 1
1, 2, 2, 8, 2, 52, 2, 128, 170, 764, 2, 2488, 2, 11624, 16928, 32768, 2, 181324, 2, 555296, 931610, 2802584, 2, 11007664, 6643782, 43955032, 44739242, 136585808, 2, 720895864, 2, 2147483648, 3250384970, 10923540812, 11517062218 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..35.

FORMULA

a(n) = 2^n-Sum{binomial[n, k]; k>0, GCD[n, k]=1}, for n>1.

a(n) = 2 for primes.

EXAMPLE

For n=6, a(6)=52 because the sum of coefficients is restricted only to k=1,5 so a(6)=64-6-6.

PROG

(PARI) a(n) = if (n==1, 1, 2^n - sum(k=0, n, if (gcd(n, k) == 1, binomial(n, k)))); \\ Michel Marcus, Mar 22 2020

CROSSREFS

Cf. A056045, A056188.

Sequence in context: A095997 A274139 A283995 * A331639 A121860 A283990

Adjacent sequences:  A056186 A056187 A056188 * A056190 A056191 A056192

KEYWORD

nonn

AUTHOR

Labos Elemer, Aug 02 2000

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 27 07:38 EST 2021. Contains 341649 sequences. (Running on oeis4.)