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(4) = 3 = 21 /7.
a077183 := [0, 2, 0, 2, 14, 15, 9, 5, 16, 4, 25, 21, 40, 67, 78, 66, 25, 111, 161, 49, 30, 15, 27, 20, 63, 98, 102, 3, 99, 92, 296, 71, 22, 367, 4, 48, 50, 91, 45, 241, 137, 258, 23, 28, 212, 40, 96, 408, 456, 110] : A055642 := proc(n) floor(log[10](n))+1 ; end : A000422 := proc(n) local resul,i; resul := 0 ; for i from n to 1 by -1 do resul := 10^A055642(i)*resul+i ; od ; end: for n from 1 to nops(a077184) do if op(n,a077184) <> 0 then printf("%a, ",A000422(op(n,a077184))/ithprime(n)) ; else printf("%d, ",0) ; fi ; od ; # R. J. Mathar, Apr 01 2007
palid(n)= { local(resul) ; resul=concat("",n) ; forstep(i=n-1,1,-1, resul=concat(i,resul) ; resul=concat(resul,i) ; ) ; return(eval(resul)) ; }
A077186(n)= { local(p) ; if(n==1 || n==3, return(0) ; ) ; p=prime(n) ; for(i=1,1500, if( palid(i)%p ==0, return(i) ; break ; ) ; ) ; return(-1) ; }
for(n=1,20, print("n=",n," k=",A077186(n)) ; ) ; \\ R. J. Mathar, May 06 2006
a(5) = 11 = 121/11.
a(5) = 12321 is a multiple of 9.
a(5) = 2 as 121 is a multiple of 11.
{ a(n) = local(p,c10,z,u,v,l,k,lk,L,q); p=prime(n); c10=Mod(10,p); z=znorder(c10); u=v=Mod(1,p); l=1; k=2; L=List(); while(1, lk=1+log(k+0.1)\log(10); if(k==10^(lk-1), L=List()); if( u*c10^(l+lk)+k*c10^l+v==0, return(k)); q=0; t=[u,v,k%p,l%z]; for(j=1,#L,if(t==L[j], q=1+#L-j)); if(q, k+=((10^lk-1-k)\q)*q; L=List(), listput(L,t)); u=u*c10^lk+k; v+=k*c10^l; l+=lk; k++) } \\ Max Alekseyev, Sep 11 2009
a(5) = 12321/9 = 1369.
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