A073866 a(n) is the smallest composite number with the sum of digits = the n-th composite number.

4, 6, 8, 9, 28, 39, 68, 69, 88, 99, 299, 399, 589, 699, 799, 899, 999, 2899, 3999, 5999, 6999, 7999, 9899, 9999, 29999, 39999, 58999, 69999, 89999, 99999, 299899, 399999, 499999, 689999, 699999, 889999, 999999, 1999999, 3899999, 3999999, 5899999, 6999999, 8999999, 9999999

Offset: 1

Author

Amarnath Murthy, Aug 15 2002

Keywords

• base
• nonn

Examples

			a(5) = 28, because 10 is the 5th composite, and 28 is the first composite with sum of digits equal to 10. - _Michel Marcus_, May 19 2014
		

Links

• Sean A. Irvine, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A002808, A073868, A075360.

Programs

PARI

lista(nn) = {vn = vector(nn, i, i); vc = select(x->iscomp(x), vn); vsd = vector(#vc, i, sumdigits(vc[i])); for (i=1, #vc, print1(vc[select(x->(x==vc[i]), vsd, 1)[1]], ", "););} \\ Michel Marcus, May 19 2014

Extensions

More terms from Michel Marcus, May 19 2014