A064143 Sum of unitary prime divisors of binomial(n, floor(n/2)).

0, 2, 3, 5, 7, 5, 12, 14, 9, 7, 23, 21, 27, 27, 29, 31, 48, 46, 62, 60, 59, 59, 81, 79, 66, 66, 59, 59, 93, 93, 124, 126, 120, 118, 125, 123, 141, 141, 158, 156, 193, 193, 225, 225, 194, 194, 243, 241, 241, 241, 245, 245, 298, 298, 321, 321, 314, 314, 365, 365, 395

Offset

1,2

Links

Harry J. Smith, Table of n, a(n) for n = 1..1000

Formula

a(n) = A063956(A001405(n)).

Prog

(PARI) a(n) = { my(f=factor(binomial(n, n\2))); sum(i=1, #f~, if (f[i, 2]==1, f[i, 1])) } \\ Harry J. Smith, Sep 09 2009

Crossrefs

Cf. A001405, A008472, A034444, A056169, A063956.

Sequence in context: A284630 A345872 A081622 * A283593 A115274 A126890

Adjacent sequences: A064140 A064141 A064142 * A064144 A064145 A064146

Keyword

nonn,changed

Author

Labos Elemer, Sep 11 2001

Status

approved