The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A271609 Number of ways to reciprocally link elements of an n X n X n triangular array with themselves or a neighbor, with no more than n elements linked to themselves. 0
 1, 3, 17, 307, 7764, 222936, 18314708, 5436984025, 1549076843600, 327785587238680, 258598550473174218, 937062960563484014011, 2266270598091075686029983, 2979993347333205027776950744, 18769591152933109773812486076631, 672356922734153057389479052479321305 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Diagonal of A271617. LINKS EXAMPLE Some solutions for n=4 .....6........0........0........6........6........0........0........0 ....6.1......6.0......0.6......0.1......6.1......0.5......4.3......4.3 ...5.1.6....0.1.6....4.3.1....0.6.6....5.1.6....0.2.6....0.0.6....5.6.0 ..2.4.3.1..4.3.0.1..0.4.3.0..0.0.1.1..2.0.0.1..4.3.0.1..4.3.0.1..2.0.1.0 Element moves: 0=itself 1=nw 2=ne 3=w 4=e 5=sw 6=se, reciprocals total 7 CROSSREFS Cf. A271617. Sequence in context: A267658 A155201 A062622 * A290806 A009592 A051294 Adjacent sequences:  A271606 A271607 A271608 * A271610 A271611 A271612 KEYWORD nonn AUTHOR R. H. Hardin, Apr 10 2016 EXTENSIONS a(13)-a(16) from Alois P. Heinz, Jun 15 2017 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified June 17 22:14 EDT 2021. Contains 345086 sequences. (Running on oeis4.)