A176601 Primes p that p//13 and p//31 are consecutive primes.
19, 853, 2287, 2467, 4243, 4513, 4621, 5431, 5701, 7243, 7477, 7591, 7927, 8221, 8317, 9283, 9439, 9817, 10039, 12781, 13933, 14461, 14923, 15727, 16693, 17443, 18199, 18217, 19207, 20749, 21139, 22147, 23761, 25471, 26701, 26953, 27481, 28111, 28447, 28579
Offset: 1
Examples
19//13 = 1913 = prime(293), 19//31 = 1931 = prime(294), 19 = prime(8) is 1st term. 853//13 = 85313 = prime(8306), 853//31 = 85331 = prime(8307), 853 = prime(147) is 2nd term.
Links
- Harvey P. Dale, Table of n, a(n) for n = 1..2000
Programs
-
Mathematica
okQ[n_]:=Module[{idn=IntegerDigits[n],p13,p31},p13=FromDigits[ Join[ idn,{1,3}]];p31=FromDigits[Join[idn,{3,1}]];PrimeQ[p13]&&NextPrime[p13] == p31]; Select[Prime[Range[16000]],okQ] (* Harvey P. Dale, Jan 21 2012 *)
Extensions
More terms from Harvey P. Dale, Jan 21 2012
Comments