A158085 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).

2, 3, 5, 7, 17, 19, 37, 59, 79, 97, 179, 197, 199, 379, 397, 577, 599, 797, 977, 997, 1979, 1997, 1999, 5779, 7759, 7993, 9199, 9397, 9739, 9973, 13799, 13997, 13999, 17599, 17959, 17977, 19597, 19759, 19777, 19979

Offset: 1

Author

Juri-Stepan Gerasimov, Mar 12 2009

Keywords

• nonn
• base
• less

Comments

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

Examples

			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
		

Programs

Maple

A158085 := proc(n)
    option remember;
    if n =1 then
        2;
    else
        for a from procname(n-1)+1 do
            if isprime(a) then
                if A071649(a) >= A071649(procname(n-1)) then
                    return a;
                end if;
            end if;
        end do:
end if; # R. J. Mathar, Feb 02 2015

Mathematica

spl[n_]:=Module[{sod=Total[Select[IntegerDigits[n],OddQ]],p1= NextPrime[ n]}, While[ Total[ Select[ IntegerDigits[ p1],OddQ]]Harvey P. Dale, Nov 15 2018 *)

Formula

A071649(a(n)) >= A071649(a(n-1)). - R. J. Mathar, Feb 02 2015

Extensions

Corrected (997 inserted, 1699 removed, 9199 to 9739 inserted) by R. J. Mathar, May 19 2010