A179444 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

A179444

Composite numbers m of the form m = 10k + 1 where k is also composite.

81, 91, 121, 141, 161, 201, 221, 261, 301, 321, 341, 351, 361, 381, 391, 441, 451, 481, 501, 511, 551, 561, 581, 621, 651, 681, 721, 741, 771, 781, 801, 841, 851, 861, 871, 901, 921, 931, 951, 961, 981, 1001, 1041, 1081, 1101, 1111, 1121, 1141, 1161, 1191, 1211, 1221, 1241, 1251, 1261, 1281, 1331

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Corresponding values of k in A179443.

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

MAPLE

select(t -> not isprime((t-1)/10) and not isprime(t), [seq(i, i=21..10001, 10)]); # Robert Israel, Jun 11 2019

MATHEMATICA

Select[10#+1&/@Select[Range[100], !PrimeQ[#]&], !PrimeQ[#]&] (* Harvey P. Dale, Dec 01 2013 *)

CROSSREFS