A116185 Numbers k such that k concatenated with k+4 gives the product of two numbers which differ by 3.

150, 186, 324, 376, 666, 2046, 3000, 82650, 100384, 466716, 1322316, 4049584, 67820074, 110003884, 135734074, 156502836, 196043286, 213017754, 238849000, 261405396, 289940826, 310507774, 365294050, 398891964, 446667216

Offset

1,1

Comments

Also numbers k such that k concatenated with k+6 gives the product of two numbers which differ by 1.

Links

Table of n, a(n) for n=1..25.

Maple

cc:=proc(x, y) local s: s:=proc(m) nops(convert(m, base, 10)) end: x*10^s(y)+y: end: a:=proc(n) if type(sqrt(9+4*cc(n, n+4)), integer) then n else fi end: seq(a(n), n=1..500000); # very slow; cc yields the concatenation of x and y; - Emeric Deutsch, May 05 2007

Crossrefs

Cf. A116112, A115428, A115429, A116316, A116199, A116172, A116329.

Sequence in context: A104262 A048706 A054729 * A008889 A184075 A207044

Adjacent sequences: A116182 A116183 A116184 * A116186 A116187 A116188

Keyword

nonn,base

Author

Giovanni Resta, Feb 06 2006

Extensions

Edited by N. J. A. Sloane, Apr 14 2007

Status

approved