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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A176590 Numbers n such that both concatenation of divisors of n and reverse concatenation of divisors of n are nonprime. 0
1, 2, 5, 6, 8, 10, 11, 12, 14, 15, 16, 17, 18, 20, 22, 23, 24, 26, 27, 28, 29, 30, 32, 33, 34, 35, 36, 38, 40, 41, 42, 44, 45, 46, 47, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 68, 69, 70, 71, 72, 74, 75, 76, 77, 78, 80, 81, 82, 83, 84, 85, 86, 87, 88 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

See A037278(n) = concatenation of divisors of n and A176558(n) = reverse concatenation of divisors of n. See A176554, A175354. Sequence of corresponding values of concatenations of divisors of a(n): {1, 12, 15, 1236, 1248, 12510, 111, ...), sequence of corresponding values of reverse concatenations of divisors of a(n): {1, 21, 51, 6321, 8421, 10521, 111, ...).

LINKS

Table of n, a(n) for n=1..72.

EXAMPLE

For n = 6; a(6) = 10; divisors of 10: 1, 2, 5, 10; both concatenation of divisors 12510 and reverse concatenation of divisors 10521 are nonprime numbers.

CROSSREFS

Sequence in context: A176114 A057915 A154329 * A253061 A320730 A087943

Adjacent sequences:  A176587 A176588 A176589 * A176591 A176592 A176593

KEYWORD

nonn,base

AUTHOR

Jaroslav Krizek, Apr 21 2010

EXTENSIONS

Extended and revised by Charles R Greathouse IV, Apr 24 2010

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
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 18 12:18 EDT 2019. Contains 328160 sequences. (Running on oeis4.)