A080464 Product of the two numbers formed by alternate digits of n.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 0, 3, 6, 9, 12, 15, 18, 21, 24, 27, 0, 4, 8, 12, 16, 20, 24, 28, 32, 36, 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 0, 6, 12, 18, 24, 30, 36, 42, 48, 54, 0, 7, 14, 21, 28, 35, 42, 49, 56, 63, 0, 8, 16, 24, 32, 40, 48, 56, 64, 72, 0

Offset: 10

Author

Amarnath Murthy, Mar 02 2003

Keywords

• base
• easy
• nonn
• look

Examples

			a(132546) = 124 * 356 = 44144.
		

Links

• M. F. Hasler, Table of n, a(n) for n = 10..10000

Crossrefs

Cf. A007954, A080463, A080465, A087471, A087472, A087473, A087474.

Programs

Mathematica

nad[n_]:=Module[{idn=IntegerDigits[n]},FromDigits[Take[idn,{1,-1,2}]] FromDigits[ Take[idn,{2,-1,2}]]]; Array[nad,120,10] (* Harvey P. Dale, Aug 07 2019 *)

PARI

A080464(n,d=digits(n))={n=d*matrix(#d,2,z,s,if((z-s)%2,10^((#d-z)\2)));n[1]*n[2]}

Formula

a(n) < n for all n. - M. F. Hasler, Jan 10 2016

Extensions

More terms from Ray Chandler, Oct 11 2003