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 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. 3
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS 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} ] CROSSREFS Sequence in context: A212801 A147565 A022167 * A267318 A050154 A179454 Adjacent sequences:  A064278 A064279 A064280 * A064282 A064283 A064284 KEYWORD nonn AUTHOR Robert G. Wilson v, Oct 14 2001 STATUS approved

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Last modified October 14 07:31 EDT 2019. Contains 327995 sequences. (Running on oeis4.)