login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A106708 Replace n with the concatenation of its proper divisors (a(n) = 0 unless n is composite). 10
0, 0, 0, 2, 0, 23, 0, 24, 3, 25, 0, 2346, 0, 27, 35, 248, 0, 2369, 0, 24510, 37, 211, 0, 2346812, 5, 213, 39, 24714, 0, 23561015, 0, 24816, 311, 217, 57, 234691218, 0, 219, 313, 24581020, 0, 23671421, 0, 241122, 35915, 223, 0, 23468121624, 7, 251025, 317 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Klaus Brockhaus, Table of n, a(n) for n=1..5000

FORMULA

a(n) = A037279(n)*A010051(n). - R. J. Mathar, Aug 01 2007

MAPLE

A106708 := proc(n) local dvs ; if isprime(n) or n = 1 then 0; else dvs := [op(numtheory[divisors](n) minus {1, n} )] ; dvs := sort(dvs) ; cat(op(dvs)) ; fi ; end: seq(A106708(n), n=1..80) ; # R. J. Mathar, Aug 01 2007

PROG

(PARI) {map(n) = local(d); d=divisors(n); if(#d<3, 0, d[1]=""; eval(concat(vecextract(d, concat("..", #d-1)))))} for(n=1, 51, print1(map(n), ", ")) /* Klaus Brockhaus, Aug 05 2007 */

(Haskell)

a106708 1           = 0

a106708 n

   | a010051 n == 1 = 0

   | otherwise = read $ concat $ (map show) $ init $ tail $ a027750_row n

-- Reinhard Zumkeller, May 01 2012

CROSSREFS

Cf. A037278, A120712, A037279, A131983 (records), A131984 (where records occur).

Cf. A027750, A010051, A037285, A037277.

Sequence in context: A293938 A254042 A009378 * A138551 A133490 A051728

Adjacent sequences:  A106705 A106706 A106707 * A106709 A106710 A106711

KEYWORD

nonn,base

AUTHOR

N. J. A. Sloane, Jul 20 2007

EXTENSIONS

More terms from R. J. Mathar and Klaus Brockhaus, Aug 01 2007

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified February 21 00:32 EST 2018. Contains 299388 sequences. (Running on oeis4.)