A191367 a(n) is the smallest sum of 2 distinct positive cubes such that n*a(n) is also sum of 2 distinct positive cubes.

9, 728, 2457, 189, 189, 126, 91, 9, 1001, 28, 91, 126, 133, 9, 2331, 91, 91, 189, 91, 854, 9, 133, 133, 2457, 217, 28, 9, 126, 217, 468, 133, 189, 3528, 11772, 637, 28, 133, 28, 9, 189, 637, 468, 217, 559, 152, 637, 559, 126, 72, 637, 5256, 9, 793, 28, 793

Offset: 1

Author

Zak Seidov, Jun 01 2011

Keywords

• nonn

Comments

a(n) and n*a(n) are terms of A024670 (Numbers that are sums of 2 distinct positive cubes); a(n)=9 if n is in A191352.

Examples

			{n,a(n),b,c,n*a(n),d,e}={1,9,1,2,9,1,2},{2,728,6,8,1456,5,11},{3,2457,9,12,7371,8,19},...
		

Links

• Chai Wah Wu, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A024670, A191352.

Formula

a(n)=b^3+c^3, n*a(n)=d^3+e^3.