A080185 Primes p such that 5 is the largest of all prime factors of the numbers between p and the next prime (cf. A052248).

7, 29, 59, 149, 179, 239, 269, 599, 809, 1619, 2999, 4049, 4799, 8999, 9719, 15359, 21599, 23039, 33749, 138239, 179999, 281249, 345599, 737279, 3455999, 6143999, 6560999, 10124999, 13668749, 15551999, 17495999, 20995199, 22118399, 23999999

Offset

1,1

Comments

The sequence consists of 7 and the lesser of twin primes q (A001359) such that q+1 is 5-smooth (A051037) but not 3-smooth (A003586, A080193).

Links

Amiram Eldar, Table of n, a(n) for n = 1..1000

Example

7 is a term since 8 = 2^3, 9 = 3^3, 10 = 2*5 are the numbers between 7 and the next prime 11; 149 is a term since 150 = 2*3*5^2 is the only number between 149 and the next prime 151.

Prog

(PARI) {forprime(p=2, 24000000, q=nextprime(p+1); m=0; j=p+1; while(j<q&&m<=5, f=factor(j); a=f[matsize(f)[1], 1]; if(m<a, m=a); j++); if(m==5, print1(p, ", ")))}

Crossrefs

Cf. A052248, A001359, A051037, A003586, A080193.

Sequence in context: A084201 A031380 A005698 * A355920 A219835 A041621

Adjacent sequences: A080182 A080183 A080184 * A080186 A080187 A080188

Keyword

nonn

Author

Klaus Brockhaus, Feb 10 2003

Status

approved