A116172 Numbers k such that k concatenated with k+2 gives the product of two numbers which differ by 5.

2, 74, 59264, 510782, 906902, 81790664, 92776472, 10876856041862, 11796926254874, 18332259798794, 18388650720624, 32624670587648, 32699883214248, 43103618706398, 44916698243804, 66132258426302

Offset

1,1

Comments

Also numbers k such that k concatenated with k+6 gives the product of two numbers which differ by 3.

Also numbers k such that k concatenated with k+8 gives the product of two numbers which differ by 1.

If k+2 and k-4 have the same number of digits, then k is also in A116132 because k//k+2 = 10^d*k + k + 2 = m*(m+5) then implies k//k-4 = 10^d*k + k - 4 = m*(m+5) - 6 = (m-1)*(m+6). - R. J. Mathar, Aug 10 2008

Links

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

Example

92776472//92776474 = 96320542 * 96320547, where // denotes concatenation.
92776472//92776480 = 96320544 * 96320545.
92776472//92776478 = 96320543 * 96320546.

Crossrefs

Cf. A116158, A116171, A116173, A116179, A116303.

Cf. A116185, A115430, A116205, A116343, A116200, A116330.

Sequence in context: A322281 A282878 A062552 * A358383 A238820 A000329

Adjacent sequences: A116169 A116170 A116171 * A116173 A116174 A116175

Keyword

nonn,base

Author

Giovanni Resta, Feb 06 2006

Extensions

Edited by N. J. A. Sloane, Apr 15 2007

Status

approved