login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A075053 Number of primes (counted with repetition) that can be formed by rearranging some or all of the digits of n. 10
0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1, 1, 3, 1, 1, 1, 3, 0, 1, 1, 1, 2, 3, 1, 2, 1, 2, 1, 2, 1, 3, 3, 2, 2, 3, 1, 4, 2, 1, 0, 1, 1, 2, 0, 1, 0, 2, 0, 0, 1, 1, 2, 3, 1, 2, 1, 2, 1, 2, 0, 1, 1, 1, 0, 1, 0, 2, 0, 0, 1, 3, 2, 4, 2, 2, 2, 2, 1, 3, 0, 0, 1, 2, 0, 1, 0, 1, 0, 1, 0, 1, 2, 1, 0, 2, 0, 3, 1, 0, 0, 2, 1, 4, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,14

COMMENTS

"Counted with repetition" means that if the same prime can be obtained using different digits, then it is counted several times (e.g., 13 obtained from 113 using the 1st and 3rd digits or the 2nd and 3rd digits), but not so if it is obtained as different permutations of the same digits (e.g., a(11)=1 because the identical permutation and the transposition (2,1) of the digits [1,1] both yield 11, but this does not count twice since the same digits are used). - M. F. Hasler, Mar 12 2014

LINKS

T. D. Noe, Table of n, a(n) for n = 0..10000

EXAMPLE

From 17 we can obtain 7, 17 and 71 so a(17) = 3. From 22 we obtain 2 in two ways, so a(22) = 2.

MATHEMATICA

f[n_] := Length@ Select[ Union[ FromDigits@# & /@ Flatten[ Subsets@# & /@ Permutations@ IntegerDigits@ n, 1]], PrimeQ@# &]; Array[f, 105, 0] (* Robert G. Wilson v, Mar 12 2014 *)

PROG

(PARI) A075053(n)={my(S=0, D, t, d); for(L=1, #D=vecsort(digits(n)), t=vector(L, i, 10^(i-1))~; forvec(i=vector(L, j, [1, #D]), d=vecextract(D, i); P=[]; for(k=1, L!, isprime(p=vecextract(d, numtoperm(L, k))*t)&&p>t[L]&&P=setunion(P, Set(p))); S+=#P, 2)); S} \\ M. F. Hasler, Mar 12 2014

CROSSREFS

Different from A039993. Cf. A072857, A076449, A039999.

Cf. A039999.

Sequence in context: A325669 A068153 A039993 * A007362 A214709 A060268

Adjacent sequences:  A075050 A075051 A075052 * A075054 A075055 A075056

KEYWORD

nonn,base,easy

AUTHOR

N. J. A. Sloane, Oct 12 2002

EXTENSIONS

Corrected and extended by John W. Layman, Oct 15 2002

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 May 22 21:05 EDT 2019. Contains 323503 sequences. (Running on oeis4.)