0,3

Let M_n be the n X n matrix m_(i,j)=3+abs(i-j) then det(M_n)=(-1)^(n+1)*a(n+1) - Benoit Cloitre (benoit7848c(AT)orange.fr), May 28 2002

If X_1,X_2,...,X_n are 2-blocks of a (2n+3)-set X then, for n>=1, a(n+2) is the number of (n+1)-subsets of X intersecting each X_i, (i=1,2,...,n). - Milan R. Janjic (agnus(AT)blic.net), Nov 18 2007

Paul Barry, A Catalan Transform and Related Transformations on Integer Sequences, Journal of Integer Sequences, Vol. 8 (2005), Article 05.4.5.

Milan Janjic, Two Enumerative Functions

F. Ellermann, Illustration of binomial transforms

Sum_{ k = 0..n } (k+3)!*binomial(n,k) gives the sequence with a different offset: 3, 7, 16, 36, 80, 176, 384, 832, 1792, 3840, 8192, ... - njas, Jan 30 2008

a(n) = (n+4)*2^(n-3), n >= 2; a(0)=1=a(1); G.f.: (1-x)^3/(1-2*x)^2.

Binomial transform of A027656.

Starting 1, 3, 7, 16.. this is ((n+5)2^n-0^n)/4, the binomial transform of (1, 2, 2, 3, 3, ...). - Paul Barry (pbarry(AT)wit.ie), May 20 2003

a(n)=(n+4)*2^(n-3)+3C(0, n)/4-C(1, n)/4; a(n)=sum{k=0..floor(n/2), C(n, 2k)(k+1)}. - Paul Barry (pbarry(AT)wit.ie), Nov 29 2004

Sequence in context: A023523 A065979 A106463 this_sequence A081037 A019489 A077852

Adjacent sequences: A045888 A045889 A045890 this_sequence A045892 A045893 A045894

easy,nonn,nice

Wolfdieter Lang (wolfdieter.lang(AT)physik.uni-karlsruhe.de)