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A169903 Primitive primes in carryless arithmetic mod 10. 2
21, 23, 25, 27, 29, 51, 56, 201, 209, 227, 229, 241, 243, 261, 263, 287, 289, 551, 2023, 2027, 2043, 2047, 2061, 2069, 2081, 2089, 2207, 2209, 2221, 2223, 2263, 2267, 2281, 2287, 2401, 2407, 2421, 2423, 2441, 2449, 2483, 2489, 2603, 2609 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Define the units in carryless arithmetic mod 10 to be the numbers 1, 3, 7 and 9 (these divide any number). A prime is a number N, not a unit, whose only factorizations are of the form N = u * M, where u is a unit.

A prime is primitive if it not the carryless product of a smaller prime and a unit.

A subsequence of A169887.

LINKS

David Applegate, Table of n, a(n) for n = 1..843 (all primitive primes with <= 6 digits)

Index entries for sequences related to carryless arithmetic

CROSSREFS

Cf. A004520, A059729, A168294, A168541, A169885, A169886, A169884, A169887.

Cf. A058943, A058945.

Sequence in context: A007929 A143712 A163396 * A095447 A095443 A095441

Adjacent sequences:  A169900 A169901 A169902 * A169904 A169905 A169906

KEYWORD

nonn,base

AUTHOR

David Applegate, Marc LeBrun and N. J. A. Sloane, Jul 11 2010

STATUS

approved

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Last modified October 17 16:51 EDT 2019. Contains 328120 sequences. (Running on oeis4.)