A057628 - OEIS

%I #19 Dec 31 2023 10:31:43

%S 11,31,53,131,149,223,283,311,313,331,397,463,641,691,937,941,1439,

%T 1511,1741,1871,1949,1993,1999,2111,2447,2939,3163,3391,3433,3499,

%U 3559,3593,3659,3911,3931,5227,5399,5923,6163,6269,6653,6719,7177,7741,8389

%N Primes such that replacing each digit d with d copies of the digit d produces a prime. Zeros are not allowed.

%C "Replacing each digit d with d copies of the digit d" is the function A048376. Therefore this is the largest subset of A038618 stable under the map A048376.

%e E.g. 641 becomes 66666644441 which is also prime.

%t Select[Prime[Range[1500]],PrimeQ[FromDigits[Flatten[Table[#,{#}]&/@ IntegerDigits[#]]]]&&DigitCount[#,10,0]==0&]  (* _Harvey P. Dale_, Mar 27 2011 *)

%o (PARI) is_A057628(n)={vecmin(digits(n)) && is_A057630(n)} \\ _M. F. Hasler_, Jan 23 2013

%Y Cf. A038618, A048376, A057630.

%K nonn,base,nice,easy

%O 1,1

%A _G. L. Honaker, Jr._, Oct 10 2000

%E More terms from _Patrick De Geest_, Oct 15 2000.

%E Offset changed to 1, according to OEIS conventions, by _M. F. Hasler_, Jan 23 2013