1,1

A109987 is semiprimes ordered alphabetically by where they occur in A000052. A109988 is 3-almost primes ordered alphabetically by where they occur in A000052.

a(1) = 5 because five is the first prime in alphabetical order.

a(4) = 89 because eighty-nine is the first 2-digit prime in alphabetical order.

Cf. A000040, A000052, A109987, A109988.

Adjacent sequences: A109983 A109984 A109985 this_sequence A109987 A109988 A109989

Sequence in context: A011316 A076567 A058091 this_sequence A021868 A011497 A010488

base,easy,nonn,word

Jonathan Vos Post (jvospost3(AT)gmail.com), Jul 07 2005