A115428 Numbers k such that the concatenation of k with k+5 gives a square.

1, 4, 20, 31, 14564, 38239, 69919, 120395, 426436, 902596, 7478020, 9090220, 6671332084, 8114264059, 8482227259, 9900250996, 2244338786836, 2490577152964, 2509440638591, 2769448208395, 7012067592220

Offset: 1

Author

Giovanni Resta, Feb 06 2006

Keywords

• nonn
• base

Comments

Also numbers k such that k concatenated with k+1 gives the product of two numbers which differ by 4.

Also numbers k such that k concatenated with k+4 gives the product of two numbers which differ by 2.

Examples

			14564_14569 = 38163^2.
		

Crossrefs

Cf. A030465, A102567, A115426, A115437, A115429, A115430, A115431, A115432, A115433, A115434, A115435, A115436, A115439.

Cf. A116125, A116099, A116167, A116297, A116177, A116171, A116185, A116315.

Extensions

Edited by N. J. A. Sloane, Apr 13 2007