A052494 Number of different primes that can be formed by permuting digits of n-th prime.

1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 2, 2, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 1, 1, 2, 1, 1, 2, 1, 3, 2, 3, 3, 2, 4, 1, 3, 3, 3, 3, 4, 2, 2, 2, 4, 3, 1, 1, 1, 1, 1, 2, 2, 2, 1, 1, 1, 2, 2, 2, 2, 2, 1, 3, 2, 3, 2, 3, 2, 2, 1, 3, 2, 3, 4, 1, 3, 4, 1, 1, 4, 2, 1, 1, 2, 1, 1, 2, 2, 2, 2, 2, 1, 4, 1, 1, 1, 2, 1, 1, 2, 1, 2, 2, 3

Offset

2,6

Comments

Leading zeros not permitted, so, e.g., prime(27) = 103 but a(27) = 1 even though 13 and 31 are both primes. - Harvey P. Dale, Dec 17 2012

Links

Table of n, a(n) for n=2..106.

Example

a(75)=4 because the digits in 379 may be arranged to form a total of 4 primes: 379, 397, 739 and 937.

Mathematica

ndp[n_]:=Module[{pers=FromDigits/@Permutations[IntegerDigits[n]]}, Count[ pers, _?(IntegerLength[#]==IntegerLength[n]&&PrimeQ[#]&)]]; ndp/@ Prime[ Range[110]] (* Harvey P. Dale, Dec 17 2012 *)

Crossrefs

A039999, A046810.

Sequence in context: A274109 A083019 A137865 * A317756 A039998 A316089

Adjacent sequences: A052491 A052492 A052493 * A052495 A052496 A052497

Keyword

base,easy,nonn

Author

Enoch Haga, Mar 16 2000

Status

approved