A214755 Primes formed by concatenating odd primes.

37, 53, 73, 113, 137, 173, 193, 197, 233, 293, 311, 313, 317, 331, 337, 347, 353, 359, 367, 373, 379, 383, 389, 397, 433, 523, 541, 547, 557, 571, 577, 593, 613, 617, 673, 677, 719, 733, 743, 757, 761, 773, 797, 977, 1013, 1033, 1093, 1097, 1117, 1123, 1129, 1153

Offset: 1

Author

Alex Ratushnyak, Aug 03 2012

Keywords

• nonn
• base

Comments

Subsequence of A019549.

Links

• David Radcliffe, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A019549, A214754.

Programs

Python

from sympy import primerange
oddPrimes = list(primerange(3, 1154))
def tryPartitioning(binString):  # First digit is not 0
    l = len(binString)
    for t in range(1, l):
        substr1 = binString[:t]
        if (int(substr1) in oddPrimes) or (t>=2 and tryPartitioning(substr1)):
            substr2 = binString[t:]
            if substr2[0]!='0':
                if (int(substr2) in oddPrimes) or (l-t>=2 and tryPartitioning(substr2)):
                    return 1
    return 0
for p in oddPrimes:
    if tryPartitioning(str(p)):
        print(p, end=', ')