A152652 Least prime p with digit sum A047235(n).

2, 13, 17, 19, 59, 79, 389, 499, 1889, 1999, 6899, 17989, 39989, 49999, 98999, 199999, 599999, 799999, 2999999, 4999999, 9899999, 19999999, 59999999, 189997999, 389999999, 689899999, 998999999, 2999899999, 6999999989, 9899989999, 39899999999, 68899999999, 98999999999

Offset

1,1

Links

David A. Corneth, Table of n, a(n) for n = 1..1713

Formula

{min A000040(i): A007605(i) = A047234(n)}. - R. J. Mathar, Dec 12 2008

Prog

(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
(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

Crossrefs

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

Cf. A000040, A007605, A047234, A047235.

Sequence in context: A153507 A124277 A038889 * A142339 A348633 A105913

Adjacent sequences: A152649 A152650 A152651 * A152653 A152654 A152655

Keyword

nonn,base

Author

Giovanni Teofilatto, Dec 10 2008

Extensions

Edited and extended by R. J. Mathar, Dec 12 2008

a(20)-a(22) from Klaus Brockhaus, Dec 13 2008

More terms from Jinyuan Wang, Jun 13 2020

Status

approved