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%I #24 Sep 08 2022 08:45:39
%S 2,13,17,19,59,79,389,499,1889,1999,6899,17989,39989,49999,98999,
%T 199999,599999,799999,2999999,4999999,9899999,19999999,59999999,
%U 189997999,389999999,689899999,998999999,2999899999,6999999989,9899989999,39899999999,68899999999,98999999999
%N Least prime p with digit sum A047235(n).
%H David A. Corneth, <a href="/A152652/b152652.txt">Table of n, a(n) for n = 1..1713</a>
%F {min A000040(i): A007605(i) = A047234(n)}. - _R. J. Mathar_, Dec 12 2008
%o (Magma) T:=[ n eq 1 select 2 else Self(n-1)+2*(1+n mod 2): n in [1..22] ]; S:=[]; p:=2; for k in T do while &+Intseq(p, 10) ne k do p:=NextPrime(p); end while; Append(~S,p); end for; S; // _Klaus Brockhaus_, Dec 13 2008
%o (PARI) a(n) = {n = (n-1)\2*6+3+(-1)^n ; t = ceil(n/9); leastfound = oo; while(leastfound == oo, my(p = partitions(n, [1,9], [t,t])); v = vector(#p, i, oo); for(i = 1, #p, if(fromdigits(Vec(p[i])) > leastfound, next(2)); forperm(Vec(p[i]), q, if(isprime(fromdigits(Vec(q))), leastfound = min(leastfound, fromdigits(Vec(q))); v[i] = min(v[i], fromdigits(Vec(q))); next(2); ) ) ); t++ ); leastfound }\\ _David A. Corneth_, Jun 13 2020
%Y Cf. A111380 (smallest prime whose digital sum is equal to the n-th composite number not congruent to 0 (modulo 3)). - _Klaus Brockhaus_, Dec 12 2008
%Y Cf. A000040, A007605, A047234, A047235.
%K nonn,base
%O 1,1
%A _Giovanni Teofilatto_, Dec 10 2008
%E Edited and extended by _R. J. Mathar_, Dec 12 2008
%E a(20)-a(22) from _Klaus Brockhaus_, Dec 13 2008
%E More terms from _Jinyuan Wang_, Jun 13 2020
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