

A027378


Expansion of (1+x^2x^3)/(1x)^4.


0



1, 4, 11, 23, 41, 66, 99, 141, 193, 256, 331, 419, 521, 638, 771, 921, 1089, 1276, 1483, 1711, 1961, 2234, 2531, 2853, 3201, 3576, 3979, 4411, 4873, 5366, 5891, 6449, 7041, 7668, 8331, 9031, 9769, 10546
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

0,2


COMMENTS

If Y is a 3subset of an nset X then, for n>=4, a(n4) is the number of (n3)subsets of X which have no exactly one element in common with Y.  Milan Janjic, Dec 28 2007


LINKS

Table of n, a(n) for n=0..37.
Index entries for linear recurrences with constant coefficients, signature (4,6,4,1).


FORMULA

a(n3)=binomial(n,3)3*n+9, n=4,5,6,....  Milan Janjic, Dec 28 2007


MATHEMATICA

CoefficientList[Series[(1+x^2x^3)/(1x)^4, {x, 0, 50}], x] (* or *) LinearRecurrence[{4, 6, 4, 1}, {1, 4, 11, 23}, 50] (* Harvey P. Dale, May 17 2021 *)


CROSSREFS

Sequence in context: A009907 A301159 A298023 * A131177 A092498 A301165
Adjacent sequences: A027375 A027376 A027377 * A027379 A027380 A027381


KEYWORD

nonn,easy


AUTHOR

N. J. A. Sloane.


STATUS

approved



