This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
a(1) = A052015(4), a(2) = A052015(15), a(3) = A052015(35), a(4) = A052015(61), ... In short, a(n) = A052015(b(n)) with b = (4, 15, 35, 61, 81, 94, 98, 100). - _M. F. Hasler_, May 03 2017
A071363(n,u=vectorv(n,i,10^(n-i)))={forvec(d=vector(n,i,[1,9]),isprime(d*u)&&n=d*u,2);n} \\ M. F. Hasler, May 03 2017
Table[Min[Select[FromDigits[Flatten[IntegerDigits[#]]]&/@ Partition[ Range[ 1000,1,-1],n,1],PrimeQ]],{n,20}]/.\[Infinity]->0 (* Harvey P. Dale, Jun 03 2019 *)
For n = 7 we have a(7) = 7 so the seven consecutive ascending numbers 7,8,9,10,11,12 and 13 concatenated together gives the smallest possible prime of this form, 78910111213.
isok(vc) = {my(x=""); for (i=1, #vc, x = concat(x, Str(vc[i]))); ispseudoprime(eval(x));}
a(n) = if (n % 3, for(i=1, oo, my(vc = vector(n, k, k+i-1)); if (isok(vc), return(i))), 0); \\ Michel Marcus, Mar 04 2021
For n = 8 we have a(8) = 46 so the eight consecutive descending numbers 46,45,44,43,42,41,40 and 39 concatenated together gives the smallest possible prime of this form, 4645444342414039.
a(4) = 23252729 as a concatenation of 23,25,27 and 29. a(3) = 0 for a concatenation of 3 odd numbers is always a multiple of 3.
d[n_]:=IntegerDigits[n]; t={3}; Do[If[Mod[m,3]==0,x=0,k=1; While[!PrimeQ[x=FromDigits[Fold[Join,d[k],Table[d[k+2n],{n,m-1}]]]],k++]]; AppendTo[t,x],{m,2,15}]; t (* Jayanta Basu, May 21 2013 *)
4_5_6_7_8_9_10_11_12_13 is a prime number.
Select[FromDigits[Flatten[IntegerDigits[#]]]&/@Partition[Range[300], 10, 1], PrimeQ] (* Vincenzo Librandi, Sep 15 2015 *)
for(n=1, 1e3, if(isprime(k=eval(Str(n, n+1, n+2, n+3, n+4, n+5, n+6, n+7, n+8, n+9))), print1(k", ")))
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