1,3

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Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.

Equals (A006535 + A030225)/2.

Cf. A036359, A002216, A005963, A000228, A001998, A018190.

Cf. A001207, A057973.

Adjacent sequences: A000225 A000226 A000227 this_sequence A000229 A000230 A000231

Sequence in context: A070766 A111772 A018190 this_sequence A108070 A038147 A082271

nonn,nice,hard

N. J. A. Sloane (njas(AT)research.att.com).

a(13) from Achim Flammenkamp (achim(AT)uni-bielefeld.de) Feb 15 1999. a(14) from Brendan Owen, Dec 31, 2001

a(15) from Joseph Myers (jsm(AT)polyomino.org.uk), May 05 2002

a(16)-a(20) from Joseph Myers (jsm(AT)polyomino.org.uk), Sep 21 2002

a(21) from Herman Jamke (hermanjamke(AT)fastmail.fm), May 05 2007