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%I #7 Sep 18 2015 05:12:57
%S 11,2,3,41,5,61,7,83,19,101,11,127,13,149,151,163,17,181,19,2003,421,
%T 223,23,241,251,263,127,281,29,307,31,3203,233,347,353,367,37,383,139,
%U 401,41,421,43,443,457,461,47,487,149,503,151,521,53,541,557,563,157,587,59,601,61,6203,163
%N Smallest prime ending (least significant side) in n if possible else beginning in n.
%p read("transforms)"):
%p nleadzero := proc(n,dgs)
%p local ndgs ;
%p if n = 0 then
%p ndgs := 0 ;
%p else
%p ndgs := ilog10(n)+1 ;
%p end if;
%p [op(convert(n,base,10)),seq(0,i=1..dgs-ndgs)]
%p end proc:
%p digcatL2 := proc(L1,L2)
%p digcatL([op(L1),op(L2)]) ;
%p end proc:
%p A089754 := proc(n)
%p local prep,a,dgs ;
%p if isprime(n) then
%p n;
%p elif modp(n,2) = 0 or modp(n,5) = 0 then
%p ndgs := convert(n,base,10) ;
%p for dgs from 1 do
%p for prep from 0 to 10^dgs-1 do
%p a := digcatL2(ListTools[Reverse](ndgs),ListTools[Reverse](nleadzero(prep,dgs))) ;
%p if isprime(a) then
%p return a;
%p end if;
%p end do:
%p end do:
%p else
%p for prep from 1 do
%p a := digcat2(prep,n) ;
%p if isprime(a) then
%p return a;
%p end if;
%p end do:
%p end if;
%p end proc: # _R. J. Mathar_, Sep 18 2015
%Y Cf. A018800, A062584, A068164.
%K base,easy,nonn
%O 1,1
%A _Amarnath Murthy_, Nov 22 2003
%E Corrected by _R. J. Mathar_, Sep 18 2015
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