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

1,2

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.

Links

Table of n, a(n) for n=1..21.

Example

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.

Sequence in context: A181433 A079454 A205670 * A172624 A043880 A030002

Adjacent sequences: A115425 A115426 A115427 * A115429 A115430 A115431

Keyword

nonn,base

Author

Giovanni Resta, Feb 06 2006

Extensions

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

Status

approved