A050716 - OEIS

%I #17 Aug 14 2024 16:54:24

%S 13,17,23,29,37,41,43,47,53,59,61,71,79,83,97,101,103,107,109,127,131,

%T 133,139,151,157,161,173,193,211,221,223,227,251,269,281,283,301,307,

%U 311,323,329,347,349,353,371,377,401,421,457,463,479,481,487,517,523

%N Inserting a digit '6' between all adjacent digits of k makes a prime.

%H Harvey P. Dale, <a href="/A050716/b050716.txt">Table of n, a(n) for n = 1..1001</a>

%e 481 becomes 4(6)8(6)1 becomes prime 46861.

%t Select[Range[10,600],PrimeQ[FromDigits[Riffle[IntegerDigits[#],6]]]&] (* _Harvey P. Dale_, Aug 26 2013 *)

%Y Cf. A050674, A050711-A050719.

%K nonn,base

%O 1,1

%A _Patrick De Geest_, Aug 15 1999

%E Definition clarified by _Harvey P. Dale_, Aug 26 2013

%E Offset changed by _Andrew Howroyd_, Aug 14 2024