
LINKS

Table of n, a(n) for n=1..15.
P. Le Conte, Coincident Birthdays
P. Diaconis and F. Mosteller, Methods of studying coincidences, J. Amer. Statist. Assoc. 84 (1989), pp. 853861.
Bruce Levin, Exact Solutions of the Generalized Birthday Problem
B. Martin, Coincidence:Remarkable or Random
I. Peterson, Mathtrek, Birthday Surprises
Eric Weisstein's World of Mathematics, Birthday Problem.


MATHEMATICA

q[1][n_, d_] := q[1][n, d] = d!/((dn)!*d^n) // N; q[k_][n_, d_] := q[k][n, d] = Sum[ n!*d!/(d^(i* k)*i!*(k!)^i*(ni*k)!*(di)!)*Sum[ q[j][ni*k, di]*(di)^(ni* k)/d^(ni*k), {j, 1, k1}], {i, 1, Floor[n/k]}] // N; p[k_][n_, d_] := 1  Sum[q[i][n, d], {i, 1, k1}]; a[1] = 1; a[k_] := a[k] = For[n = a[k1], True, n++, If[p[k][n, 365] >= 1/2, Return[n]]]; Table[ Print["a(", k, ") = ", a[k]]; a[k], {k, 1, 15}] (* JeanFrançois Alcover, Jun 12 2013, after Eric Weisstein *)
