A153432 -id:A153432 - cp's OEIS frontend

A153431 a(n) is the smallest number m such that all n+1 numbers m*10^k+1 k=0,1, ...,n are prime.

1, 1, 1, 4, 28, 28, 170926, 170926, 931371868, 15538734736, 89468493268, 6009549731752, 89984938946056, 43000687652274618

Offset: 0

Farideh Firoozbakht, Mar 15 2009, Mar 27 2009

If n

representations of the form p*q-(p+q)where p & q are prime.

For n>3, 7 divides a(n). a(10) is greater than 4*10^10.

			28+1, 280+1, 2800+1, 28000+1, 280000+1 & 2800000+1 are prime and 28 is the smallest such number so a(5)=28.

Prime Puzzles Two Bergot questions

Cf. A153432.

a(11)-a(13) from Don Reble, Jul 06 2022

A153433 Numbers m such that all 11 numbers 10^k*m+1; k=0,1,...,9 & 10 are prime.

Original entry on oeis.org

89468493268, 342174928102, 1124855005456, 1183450662310, 1885504856592, 2425861640748, 2926121345812, 3713879215312, 3984048347706, 4181062989166, 4335021717418, 5232993739512, 6009549731752, 6406772991528, 7451945623752, 8329610667490, 8533933744882, 9374871820930, 9425264464140, 9578838492160

Offset: 1

Farideh Firoozbakht, Apr 02 2009

nonn

If m & n are in the sequence, k<11 and r=m*n*10^k -1 is prime then r has at least k+1 representations of the form p*q-(p+q)where p & q are prime.

Carlos Rivera, Two Bergot questions

Cf. A153431, A153432.

A153433 a(3)-a(20) from Don Reble, Jul 06 2022

Showing 1-2 of 2 results.

cp's OEIS Frontend

A153431 a(n) is the smallest number m such that all n+1 numbers m*10^k+1 k=0,1, ...,n are prime.

Views

Author

Keywords

Comments

Examples

Links

Crossrefs

Extensions