A155476 Primes p such that p and the p-th prime have the same largest digit.

7, 29, 37, 73, 97, 109, 137, 139, 149, 181, 239, 271, 281, 283, 293, 307, 367, 379, 397, 419, 449, 499, 557, 577, 593, 599, 631, 659, 691, 733, 751, 839, 877, 881, 883, 911, 919, 971, 977, 1109, 1129, 1193, 1229, 1249, 1283, 1289, 1291, 1307, 1429, 1489

Offset: 1

Author

Juri-Stepan Gerasimov, Jan 23 2009

Keywords

• nonn
• base

Examples

			7 (prime) is a term because prime(7)=17 and 7 and 17 have 7 as their largest digit.
29 (prime) is a term because prime(29)=109 and 29 and 109 have 9 as their largest digit.
37 (prime) is a term because prime(37)=157 and 37 and 157 have 7 as their largest digit.
		

Links

• Jinyuan Wang, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000040 (primes), A054055, A060418.

Programs

Maple

A054055 := proc(n) max( op(convert(n,base,10)) ) ; end proc:
for n from 2 to 2200 do if isprime(n) then if A054055(n) = A054055(ithprime(n)) then printf("%d,",n) ; end if; end if; end do: # R. J. Mathar, May 10 2010

PARI

forprime(p=1,1489,if(vecmax(digits(p))==vecmax(digits(prime(p))),print1(p,", "))) \\ Jinyuan Wang, Feb 13 2019

Extensions

Most terms > 300 corrected by R. J. Mathar, May 10 2010