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

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A087097 Dismal primes (cf. A087062). 21
19, 29, 39, 49, 59, 69, 79, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 109, 209, 219, 309, 319, 329, 409, 419, 429, 439, 509, 519, 529, 539, 549, 609, 619, 629, 639, 649, 659, 709, 719, 729, 739, 749, 759, 769, 809, 819, 829, 839, 849, 859, 869, 879, 901, 902, 903, 904, 905, 906, 907, 908, 909, 912, 913, 914, 915, 916, 917, 918, 919, 923, 924, 925, 926, 927, 928, 929, 934, 935, 936, 937, 938, 939, 945, 946, 947, 948, 949, 956, 957, 958, 959, 967, 968, 969, 978, 979, 989 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

9 is the multiplicative unit. A number n is a dismal prime if it is not a dismal product (see A087062 for definition) r*s where neither r nor s is 9.

All dismal primes must contain a 9, so this is a subset of A011539.

Also, numbers n such that the dismal sum of the dismal prime divisors of n is n. (From N. J. A. Sloane, Aug 23 2010)

LINKS

David Applegate and N. J. A. Sloane, Table of n, a(n) for n = 1..22095 [all primes with at most 5 digits]

D. Applegate, C program for dismal arithmetic and number theory

D. Applegate, M. LeBrun and N. J. A. Sloane, Dismal Arithmetic

Index entries for sequences related to dismal arithmetic

EXAMPLE

8 is not prime since 8 = 8*8. 9 is not prime since it is the multiplicative unit. 10 is not prime since 10 = 10*8. Thus 19 is the smallest prime.

CROSSREFS

Cf. A087062, A087636, A087638, A087984.

Sequence in context: A047985 A061763 A088474 * A038364 A151360 A109276

Adjacent sequences:  A087094 A087095 A087096 * A087098 A087099 A087100

KEYWORD

nonn,easy,base

AUTHOR

Marc LeBrun (mlb(AT)well.com), Oct 20 2003

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

Content is available under The OEIS End-User License Agreement .

Last modified February 16 01:31 EST 2012. Contains 205860 sequences.