A259144 Number of n-digit primes whose sum of digits is 7.
1, 2, 7, 20, 28, 58, 95, 154, 226, 278, 403, 570, 734, 949, 1200, 1515, 1931, 2328, 2908, 3529, 4196, 5034, 5800, 6870, 7871, 9132, 10574, 12359, 14005, 15871, 17924, 20231, 22505, 25903, 28800, 31532, 34830, 38479, 43334, 48847, 52769, 57173, 61545, 67774, 75186
Offset: 1
Links
- Giovanni Resta, Table of n, a(n) for n = 1..100
Programs
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PARI
a(n)=n--; my(A,B,C,D); sum(a=0,n, A=10^n+10^a+1; sum(b=a,n, B=A+10^b; sum(c=b,n, C=B+10^c; sum(d=c,n, D=C+10^d; sum(e=d,n, isprime(D+10^e)))))) \\ Charles R Greathouse IV, Jun 19 2015
Extensions
More terms from Alois P. Heinz, Jun 19 2015