A116116 Numbers k such that k concatenated with k-6 gives the product of two numbers which differ by 2.

21, 30, 902406, 959721, 6040059046, 6242406405, 9842410005, 9900249006, 15033519988494, 17250863148969, 22499666270469, 27632040031654, 34182546327286, 37487353123861, 52213551379230, 74230108225630

Offset

1,1

Comments

If k-6 has d digits, the concatenation is k//k-6 = 10^d*k+k-6 = m*(m+2), therefore k//k-9 = 10^d*k+k-9 = (m-1)*(m+3), so there is a large overlap or equality with A116096. Also k//k-5 = 10^d*k+k-5 = (m+1)^2, so there is a large overlap or equality with A115433. - R. J. Mathar, May 22 2026

Links

Table of n, a(n) for n=1..16.

Example

9900249006//9900249000 = 9949999500 * 9949999502, where // denotes concatenation.

Crossrefs

Cf. A116102, A116115, A115431, A115433, A116121, A116247.

Sequence in context: A228142 A276756 A116096 * A115433 A079394 A112375

Adjacent sequences: A116113 A116114 A116115 * A116117 A116118 A116119

Keyword

nonn,base,more

Author

Giovanni Resta, Feb 06 2006

Status

approved