A061248 Primes at which sum of digits strictly increases.

2, 3, 5, 7, 17, 19, 29, 59, 79, 89, 199, 389, 499, 599, 997, 1889, 1999, 2999, 4999, 6899, 8999, 29989, 39989, 49999, 59999, 79999, 98999, 199999, 389999, 598999, 599999, 799999, 989999, 2998999, 2999999, 4999999, 6999899, 8989999, 9899999

Offset: 1

Author

Amarnath Murthy, Apr 23 2001

Keywords

• nonn
• base

Examples

			a(6) = 19, sum of digits is 10; a(7) = 29, sum of digits is 11 and 11 > 10.
		

Links

• Eric M. Schmidt, Table of n, a(n) for n = 1..1000

Crossrefs

For the actual digit sums see A062132.

Programs

Mathematica

t = {s = 2}; Do[If[(y = Total[IntegerDigits[x = Prime[n]]]) > s, AppendTo[t, x]; s = y], {n, 2, 750000}]; t (* Jayanta Basu, Aug 09 2013 *)

Sage

def A061248(nterms, b=10) :
    res = []; n_list = [2]; n = 2; dsum = 0
    while len(res) < nterms :
        while not (sum(n_list) >= dsum and n.is_prime()) :
            i = next((j for j in range(len(n_list)) if n_list[j] < b-1), len(n_list))
            if i == len(n_list) : n_list.append(0)
            n_list[i] += 1
            r = dsum - sum(n_list[i:])
            for j in range(i) :
                n_list[j] = min(r, b-1)
                r -= n_list[j]
            n = sum(n_list[i]*b^i for i in range(len(n_list)))
        res.append(n); dsum = sum(n_list)+1
    return res
# Eric M. Schmidt, Oct 08 2013

Extensions

More terms from Patrick De Geest, Jun 05 2001