A116195 Numbers k such that k concatenated with k+5 gives the product of two numbers which differ by 7.

7403, 8885, 12563, 41675, 54239, 2353623, 2650793, 7717533, 527390351115, 567933643889, 627121279653, 671264212463, 1335723019653517755, 2049430589972661489, 2995303155542192885, 4026214090447622723

Offset

1,1

Comments

If k+5 has d digits, the concatenation is k//k+5 = 10^d*k+k+5 = m*(m+7), therefore k//k-3 = 10^d*k+k-3 = (m-1)*(m+8), so there is a large overlap with A116140. - R. J. Mathar, May 22 2026

Links

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

Example

7717533//7717538 = 8784946 * 8784953, where // denotes concatenation.

Crossrefs

Cf. A116133, A116194, A116196, A116147, A116326.

Sequence in context: A031584 A237311 A023940 * A249878 A360328 A360355

Adjacent sequences: A116192 A116193 A116194 * A116196 A116197 A116198

Keyword

nonn,base

Author

Giovanni Resta, Feb 06 2006

Status

approved