A087512 Primes consisting only of digits 1 and 4 occurring with equal frequency.

41, 14441411, 41414411, 44114141, 1144141441, 1144144411, 1144441141, 1411414441, 1441411441, 1441444111, 1444114141, 4111144441, 4111444411, 4114414141, 4141141441, 4141144141, 4144111441, 4411114441, 4411144141, 4411414411, 4414141141, 4414441111

Offset

0,1

Comments

There are 18 digit pairs which can produce such primes. (1, 0), (7, 0), (1, 3), (1, 4), (1, 6), (1, 7), (1, 9), (2, 3), (2, 9), (3, 4), (3, 5), (3, 7), (3, 8), (4, 7), (4, 9), (5, 9), (6, 7), (7, 9).

Links

Harvey P. Dale, Table of n, a(n) for n = 0..5000

Maple

Primes consisting only of digits x and y, occurring with equal frequency. d1=x; d2=y; k=0; a=vector(100); for(n=1, 3000, B=binary(n); L=length(B); s=sum(j=1, length(B), B[j]); if(L%2==0 & s==L/2, C=vector(L, n, (d2-d1)*B[n]+d1); p=subst(Pol(C), x, 10); if(isprime(p), if(k<100, k++; a[k]=p)); D=vector(L, n, d2-(d2-d1)*B[n]); q=subst(Pol(D), x, 10); if(isprime(q ), if(k<100, k++; a[k]=q))); ); a=vector(k, n, a[n]); vecsort(a)

Mathematica

Union[Flatten[Table[Select[FromDigits/@Permutations[Flatten[Table[{1, 4}, {n}]]], PrimeQ], {n, 5}]]] (* Harvey P. Dale, Nov 21 2014 *)

Crossrefs

Cf. A087510, A087513, A087514.

Sequence in context: A297056 A292070 A297230 * A297055 A228555 A297058

Adjacent sequences: A087509 A087510 A087511 * A087513 A087514 A087515

Keyword

base,nonn

Author

Paul D. Hanna and Amarnath Murthy, Sep 11 2003

Extensions

More terms from Harvey P. Dale, Nov 21 2014

Status

approved