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A057034
Difference between n!! and the first prime before n!! - 1.
2
3, 2, 5, 2, 5, 4, 7, 4, 7, 4, 23, 2, 19, 2, 97, 2, 19, 64, 17, 62, 19, 4, 17, 58, 23, 64, 157, 122, 47, 106, 47, 4, 29, 146, 31, 64, 29, 8, 71, 8, 43, 32, 31, 128, 67, 122, 41, 2, 37, 146, 137, 122, 191, 142, 59, 128, 71, 284, 109, 274, 101, 218, 97, 32, 83, 158, 53, 166
OFFSET
4,1
COMMENTS
Analogous to the lesser Fortunate numbers but unlike them, all entries are not prime. Must odd entries are powers of two and all even entries are primes.
MATHEMATICA
PrevPrime[ n_Integer ] := (k=n-1; While[ !PrimeQ[ k ], k-- ]; Return[ k ]); f[ n_Integer ] := (p = n!! - 1; q = PrevPrime[ p ]; Return[ p - q + 1 ]); Table[ f[ n ], {n, 4, 75} ]
CROSSREFS
Sequence in context: A112528 A366687 A154421 * A075410 A023513 A069735
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Sep 09 2000
STATUS
approved