A248794 a(n) = the smallest number k for which the sum of digits (A007953(k)) and the product of digits (A007954(k)) are both equal to highly composite numbers A002473, i.e., numbers whose prime divisors are all <= 7.

1, 2, 3, 4, 5, 6, 7, 8, 9, 11125, 111126, 1111127, 111111135, 11111128, 111111129, 1111111111145, 1111111111137, 111111111111138, 11111111111111155, 11111111111111139, 1111111111111111147, 111111111111111111156, 1111111111111111111148, 1111111111111111111111157

Offset

1,2

Comments

See comment in A034710 (positive numbers for which the sum of digits equals the product of digits).

Links

Table of n, a(n) for n=1..24.

Example

For n = 11; a(11) = 111126 because A002473(11) = 12, A007953(111126) = A007954(111126) = 12.

Prog

(Magma) A248794:=func<n|exists(r){k:k in[1..10^n] | &*Intseq(k) eq &+Intseq(k) and &*Intseq(k) eq n}select r else 0>; [A248794(n):n in[A002473(n)]]

Crossrefs

Cf. A002473, A034710, A007953, A007954.

Sequence in context: A082935 A077739 A078213 * A032555 A032559 A276142

Adjacent sequences: A248791 A248792 A248793 * A248795 A248796 A248797

Keyword

nonn,base

Author

Jaroslav Krizek, Nov 02 2014

Status

approved