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

1,1

Links

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

Example

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

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 *)

Prog

(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

Crossrefs

For the actual digit sums see A062132.

Sequence in context: A127042 A069802 A067954 * A059498 A247147 A158085

Adjacent sequences: A061245 A061246 A061247 * A061249 A061250 A061251

Keyword

nonn,base

Author

Amarnath Murthy, Apr 23 2001

Extensions

More terms from Patrick De Geest, Jun 05 2001

Status

approved