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 A067180 Smallest prime with digit sum n, or 0 if no such prime exists. 12
 0, 2, 3, 13, 5, 0, 7, 17, 0, 19, 29, 0, 67, 59, 0, 79, 89, 0, 199, 389, 0, 499, 599, 0, 997, 1889, 0, 1999, 2999, 0, 4999, 6899, 0, 17989, 8999, 0, 29989, 39989, 0, 49999, 59999, 0, 79999, 98999, 0, 199999, 389999, 0, 598999, 599999, 0, 799999, 989999, 0, 2998999, 2999999, 0, 4999999 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Robert G. Wilson v, Table of n, a(n) for n = 1..175 FORMULA a(3k) = 0 for k > 1. a(3k-2) =  A067523(2k-1), a(3k-1) = A067523(2k), for all k > 1. - M. F. Hasler, Nov 04 2018 EXAMPLE a(68) = 59999999 because 59999999 is the smallest prime with digit sum = 68; a(100) = 298999999999 because 298999999999 is the smallest prime with digit sum = 100. MATHEMATICA a = Table[0, {100}]; Do[b = Apply[ Plus, IntegerDigits[ Prime[n]]]; If[b < 101 && a[[b]] == 0, a[[b]] = Prime[n]], {n, 1, 10^7} ]; a f[n_] :=  If[n > 5 && Mod[n, 3] == 0, 0, Block[{k = 1, lmt, lst = {}, ip = IntegerPartitions[n, Round[1 + n/9], {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}]}, lmt = 1 + Length@ ip; While[k < lmt, AppendTo[lst, Select[ FromDigits@# & /@ Permutations@ ip[[k]], PrimeQ[#] &]]; k++]; Min@ Flatten@ lst]]; f[1] = 0; f[4] = 13; Array[f, 70] (* Robert G. Wilson v, Sep 28 2014 *) PROG (PARI) A067180(n)={if(n<2, 0, n<4, n, n%3, my(d=divrem(n, 9)); forprime(p=d[2]*10^d[1]-1, , sumdigits(p)==n&&return(p)))} \\ M. F. Hasler, Nov 04 2018 CROSSREFS Cf. A054750. Removal of the 0 terms from this sequence leaves A067523. Sequence in context: A196378 A051298 A069870 * A067182 A191000 A085402 Adjacent sequences:  A067177 A067178 A067179 * A067181 A067182 A067183 KEYWORD easy,nonn,base AUTHOR Amarnath Murthy, Jan 09 2002 EXTENSIONS Edited and extended by Robert G. Wilson v, Mar 01 2002 Edited by Ray Chandler, Apr 24 2007 STATUS approved

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Last modified October 22 12:47 EDT 2019. Contains 328318 sequences. (Running on oeis4.)