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A296360 Number of monohedral disk tilings of type C^t_{2n+1,3}. 4
116, 6402, 446930, 34121322, 2741227176, 227759341712, 19382568941318, 1679333068357460, 147541888215426742, 13107891004266127974, 1175188298096727647322, 106164291028322202227232, 9652457243380891557169712, 882443342536355491502025678 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Lars Blomberg, Table of n, a(n) for n = 1..100

Joel Anthony Haddley, Stephen Worsley, Infinite families of monohedral disk tilings, arXiv:1512.03794v2 [math.MG], 2015-2016.

FORMULA

a(n) = 2*Sum_{i=0..4*n+2} A241926(i, 3*(4*n+2-i)). - Andrew Howroyd, Jan 09 2018

MATHEMATICA

U[n_, k_] := DivisorSum[GCD[n, k], EulerPhi[#]*Binomial[(n + k)/#, n/#]/(n + k) &];

a[n_] := 2*Sum[U[i, 3*(4*n + 2 - i)], {i, 0, 4*n + 2}];

Array[a, 16] (* Jean-Fran├žois Alcover, Jun 14 2018, after Andrew Howroyd *)

PROG

(PARI) \\ here U is A241926

U(n, k)={sumdiv(gcd(n, k), d, eulerphi(d)*binomial((n+k)/d, n/d)/(n+k))}

a(n)={2*sum(i=0, 4*n+2, U(i, 3*(4*n+2-i)))} \\ Andrew Howroyd, Jan 09 2018

CROSSREFS

Cf. A241926, A296359, A296361, A296362.

Sequence in context: A241941 A202903 A193170 * A035814 A284377 A009617

Adjacent sequences:  A296357 A296358 A296359 * A296361 A296362 A296363

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Dec 15 2017

EXTENSIONS

Terms a(6) and beyond from Lars Blomberg, Jan 09 2018

STATUS

approved

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Last modified June 6 11:14 EDT 2020. Contains 334827 sequences. (Running on oeis4.)