A064281 Least k such that k*10^n+1, k*10^n+3, k*10^n+7 and k*10^n+9 are all prime.

4, 1, 1, 13, 676, 283, 14311, 12022, 27346, 14965, 3427, 100942, 12370, 1237, 3274, 42382, 18619, 4570, 457, 434869, 203362, 305491, 213742, 436831, 217198, 168586, 258214, 215737, 1312441, 272848, 744082, 2059111, 351055, 712333, 1880302

Offset

0,1

Links

Sean A. Irvine, Table of n, a(n) for n = 0..50

Mathematica

Do[k = 1; While[ !PrimeQ[k*10^n + 1] || !PrimeQ[k*10^n + 3] || !PrimeQ[k*10^n + 7] || !PrimeQ[k*10^n + 9], k++ ]; Print[k], {n, 0, 20} ]
lk[n_]:=Module[{k=1}, While[!AllTrue[k*10^n+{1, 3, 7, 9}, PrimeQ], k++]; k]; Array[lk, 40, 0] (* Harvey P. Dale, Sep 03 2024 *)

Crossrefs

Sequence in context: A147565 A022167 A339849 * A267318 A050154 A179454

Adjacent sequences: A064278 A064279 A064280 * A064282 A064283 A064284

Keyword

nonn

Author

Robert G. Wilson v, Oct 14 2001

Status

approved