A105526 Smallest prime that becomes a product of n distinct primes when a 1 is prepended to it.

3, 5, 113, 1193, 13883, 312311, 10861751, 209551343, 10705778183, 307525001783, 10418232047123, 795076554810539, 17714426958677549, 1015246475642397989, 100019969411961789191, 1728838135940697098327, 165000496158437438012513

Offset

1,1

Comments

We have a(2)=5 because 5 is the smallest prime (ahead of 11,19,19,23,29,...) that is a product of two distinct primes when a 1 is prepended.

Links

Table of n, a(n) for n=1..17.

Prog

(PARI) {len10(n) = ceil(log(n+1)/log(10))}
{r(n, p, d)=local(q); if(d==0, k=n-10^(len10(n)-1); if(len10(k)==len10(n)-1 && isprime(k), m=n); return); q=nextprime(p+1); while(n*q^d<m, r(n*q, q, d-1); q=nextprime(q+1))}
{A105526(d) = M=3^d; while(1, m=M; r(1, 2, d); if(m!=M, return(m%10^(len10(m)-1))); M*=2)} \\ Max Alekseyev, Apr 28 2005

Crossrefs

Cf. A105525.

Sequence in context: A054266 A054268 A153137 * A070743 A340823 A364545

Adjacent sequences: A105523 A105524 A105525 * A105527 A105528 A105529

Keyword

nonn,base,changed

Author

Lekraj Beedassy, Apr 11 2005

Extensions

a(5)-a(8) from Ray Chandler, Apr 21 2005

More terms from Max Alekseyev, Apr 28 2005

Status

approved