A104247 Primes that are the sum of digits of the first k primes for some k.
2, 5, 17, 19, 23, 31, 41, 61, 71, 83, 181, 269, 389, 419, 449, 631, 683, 727, 743, 809, 929, 1039, 1061, 1069, 1091, 1277, 1381, 1481, 1567, 1613, 1747, 1873, 1951, 1993, 2039, 2129, 2281, 2297, 2339, 2381, 2549, 2579
Offset: 1
Examples
a(4)=19 because A058049(4)= 5 and sum of digits of the first 5 primes, 2+3+5+7+(1+1)=19 is prime.
Links
- M. F. Hasler, Table of n, a(n) for n = 1..1000
Crossrefs
Programs
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Python
from sympy import isprime, nextprime def sd(n): return sum(map(int, str(n))) def aupto(limit): alst, k, p, s = [], 1, 2, 2 while s <= limit: if isprime(s): alst.append(s) k += 1; p = nextprime(p); s += sd(p) return alst print(aupto(2579)) # Michael S. Branicky, Jul 18 2021