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

 

Logo

Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 5000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A182364 a(1) = 0; a(n) = smallest integer not yet in this sequence S such that two neighboring digits of S sum to a semiprime  (4, 6, 9, 10, 14, or 15). 0
0, 4, 2, 7, 3, 1, 5, 9, 6, 8, 13, 15, 18, 19, 51, 31, 33, 36, 37, 22, 24, 27, 28, 60, 40, 42, 45, 46, 81, 54, 55, 59, 63, 64, 68, 69, 131, 82, 72, 73, 77, 78, 133, 136, 86, 87, 222, 224, 227, 228, 137, 240, 90, 91, 95, 96, 313, 151, 315, 154, 242, 245, 155, 159, 181, 318, 182, 246, 319, 186, 331, 333, 187, 272, 273, 190, 404, 277, 278, 191, 336, 337, 281, 360, 406, 363, 195, 196, 364, 282, 286, 368, 287, 369, 513, 372, 409, 515, 422, 424, 518 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

This is to A001358 semiprimes. as Eric Angelini's “Smallest integer not yet in S such that two neighboring digits of S sum up to a prime”, is to A000040 Primes. Corrected and extended by Hans Havermann.

LINKS

Table of n, a(n) for n=1..101.

EXAMPLE

a(2) = 4 because 4 is the smallest integer k such that a(0) + k is a semiprime (2*2 = 4).

CROSSREFS

Cf. A001358.

Sequence in context: A010648 A272335 A198994 * A021238 A222622 A161179

Adjacent sequences:  A182361 A182362 A182363 * A182365 A182366 A182367

KEYWORD

nonn,base,easy

AUTHOR

Jonathan Vos Post, Apr 27 2012

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 December 2 15:01 EST 2016. Contains 278678 sequences.