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A349994
a(n) is the difference between the n-th prime and the next smaller odd squarefree semiprime, divided by 2.
1
1, 2, 1, 4, 5, 1, 1, 2, 4, 1, 1, 2, 1, 1, 2, 1, 3, 1, 1, 3, 4, 6, 7, 1, 2, 1, 2, 3, 2, 3, 1, 1, 3, 6, 1, 2, 2, 3, 5, 6, 1, 1, 3, 4, 6, 1, 2, 1, 2, 2, 1, 2, 5, 7, 8, 1, 1, 1, 2, 4, 1, 1, 3, 4, 6, 2, 1, 1, 1, 1, 4, 1, 3, 1, 1, 2, 2, 3, 1, 3, 1, 2, 4, 5, 7, 3, 1, 1, 1
OFFSET
7,2
LINKS
EXAMPLE
a(7) = (17 - 15)/2 = 1,
a(8) = (19 - 15)/2 = 2,
a(9) = (23 - 21)/2 = 1,
a(10) = (29 - 21)/2 = 4.
PROG
(PARI) forprime(p=17, 500, forstep(k=p-2, 15, -2, if(omega(k)==2&&bigomega(k)==2, print1((p-k)/2, ", "); break)))
CROSSREFS
Cf. A046388.
Sequence in context: A191660 A129874 A021983 * A375123 A194363 A161135
KEYWORD
nonn
AUTHOR
Hugo Pfoertner, Dec 12 2021
STATUS
approved