A158085 - OEIS

%I #17 Nov 15 2018 06:59:18

%S 2,3,5,7,17,19,37,59,79,97,179,197,199,379,397,577,599,797,977,997,

%T 1979,1997,1999,5779,7759,7993,9199,9397,9739,9973,13799,13997,13999,

%U 17599,17959,17977,19597,19759,19777,19979

%N Starting at a(1)=2, a(n) is the smallest prime larger than a(n-1) such that the sum of odd digits of a(n) is not smaller than the sum of odd digits of a(n-1).

%C "Odd digits" means odd-valued digits (not digits in odd-indexed positions).

%F A071649(a(n)) >= A071649(a(n-1)). - _R. J. Mathar_, Feb 02 2015

%e The sequence of the sums of odd digits is 0, 3=3, 5=5, 7=7, 1+7=8, 1+9=10, 3+7=10, 5+9=14, 7+9=16, 9+7=16, 1+7+9=17, 1+9+7=17, 1+9+9=19 and so on. - _R. J. Mathar_, Feb 02 2015

%p A158085 := proc(n)

%p     option remember;

%p     if n =1 then

%p         2;

%p     else

%p         for a from procname(n-1)+1 do

%p             if isprime(a) then

%p                 if A071649(a) >= A071649(procname(n-1)) then

%p                     return a;

%p                 end if;

%p             end if;

%p         end do:

%p end if; # _R. J. Mathar_, Feb 02 2015

%t spl[n_]:=Module[{sod=Total[Select[IntegerDigits[n],OddQ]],p1= NextPrime[ n]}, While[ Total[ Select[ IntegerDigits[ p1],OddQ]]<sod, p1=NextPrime[ p1]]; p1]; NestList[spl,2,40] (* _Harvey P. Dale_, Nov 15 2018 *)

%K nonn,base,less

%O 1,1

%A _Juri-Stepan Gerasimov_, Mar 12 2009

%E Corrected (997 inserted, 1699 removed, 9199 to 9739 inserted) by _R. J. Mathar_, May 19 2010