A053547 Smallest prime starting with A000422(n).

11, 211, 3217, 432121, 543217, 65432117, 76543217, 876543211, 9876543211, 1098765432101, 11109876543211, 12111098765432101, 1312111098765432139, 141312111098765432113, 15141312111098765432173

Offset

1,1

Links

Chai Wah Wu, Table of n, a(n) for n = 1..100

Example

a(6)=65432117 is smallest prime beginning with the string 654321.

Mathematica

Flatten[Select[Join[10 #+Range[1, 9, 2], 100 #+Range[1, 99, 2]], PrimeQ, 1]&/@ Table[FromDigits[Flatten[IntegerDigits/@Range[n, 1, -1]]], {n, 25}]] (* Harvey P. Dale, Nov 04 2011 *)

Prog

(Python)
from sympy import isprime
def A053547(n):
    s = int(''.join(str(m) for m in range(n, 0, -1)))
    for i in range(1, 10):
        s *= 10
        for j in range(1, 10**i, 2):
            x = s+j
            if isprime(x):
                return x
    else:
        return 'search limit reached.' # Chai Wah Wu, Jan 02 2015

Crossrefs

Cf. A000422.

Sequence in context: A136307 A249604 A038399 * A053582 A077714 A089567

Adjacent sequences: A053544 A053545 A053546 * A053548 A053549 A053550

Keyword

easy,nice,nonn,base

Author

Enoch Haga, Jan 16 2000

Status

approved