A073865 Largest n-digit prime with digit sum n, or 0 if no such prime exists.

0, 11, 0, 3001, 30011, 0, 5001001, 61000001, 0, 9000000001, 82000000001, 0, 9210000000001, 92200000000001, 0, 9500000100000001, 97000000000000001, 0, 9800000000000010001, 98010000010000000001, 0, 9920000010000000000001, 99300010000000000000001, 0, 9950000010000000000000001

Offset

1,2

Links

Andrew Howroyd, Table of n, a(n) for n = 1..500

Prog

(PARI)
a(n)={
  my(recurse(k, r, p)=if(k==1, if(r<=9 && isprime(p+r), p+r, 0),
       my(t=0, c=min(r-1, 9));
       while(!t&&c>=0, t=self()(k-1, r-c, (p+c)*10); c--); t)) ;
  my(t=0, c=min(n, 9)); if(n%3, while(!t&&c>0, t=recurse(n-1, n-c, c*10); c--)); t
} \\ Andrew Howroyd, Dec 10 2024

Crossrefs

Cf. A073864.

Sequence in context: A287630 A073864 A277560 * A036931 A165399 A157712

Adjacent sequences: A073862 A073863 A073864 * A073866 A073867 A073868

Keyword

base,nonn

Author

Amarnath Murthy, Aug 15 2002

Extensions

a(7) onwards from Andrew Howroyd, Dec 10 2024

Status

approved