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 A038992 Sublattices of index n in generic 5-dimensional lattice. 12
 1, 31, 121, 651, 781, 3751, 2801, 11811, 11011, 24211, 16105, 78771, 30941, 86831, 94501, 200787, 88741, 341341, 137561, 508431, 338921, 499255, 292561, 1429131, 508431, 959171, 925771, 1823451, 732541, 2929531, 954305, 3309747, 1948705, 2750971, 2187581, 7168161, 1926221 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 REFERENCES M. Baake, "Solution of coincidence problem...", in R. V. Moody, ed., Math. of Long-Range Aperiodic Order, Kluwer 1997, pp. 9-44. LINKS Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..5000 from G. C. Greubel) M. Baake, N. Neumarker, A Note on the Relation Between Fixed Point and Orbit Count Sequences, JIS 12 (2009) 09.4.4, Section 3. FORMULA f(Q, n) = Sum_{d|n} d*f(Q-1, d); here Q=5. Multiplicative with a(p^e) = Product_{k=1..4} (p^(e+k)-1)/(p^k-1). Dirichlet g.f. zeta(s)*zeta(s-1)*zeta(s-2)*zeta(s-3)*zeta(s-4). Dirichlet convolution of A038991 with A000583. - R. J. Mathar, Mar 31 2011 MATHEMATICA a[n_] := DivisorSum[n, #*DivisorSum[#, #*DivisorSum[#, #*DivisorSum[#, # &] &] &] &]; Array[a, 50] (* Jean-François Alcover, Dec 02 2015, after Joerg Arndt *) f[p_, e_] := Product[(p^(e + k) - 1)/(p^k - 1), {k, 1, 4}]; a[1] = 1; a[n_] := Times @@ (f @@@ FactorInteger[n]); Array[a, 100] (* Amiram Eldar, Aug 29 2019 *) PROG (PARI) a(n)=sumdiv(n, x, x * sumdiv(x, y, y * sumdiv(y, z, z * sumdiv(z, w, w ) ) ) ); /* Joerg Arndt, Oct 07 2012 */ CROSSREFS Cf. A001001, A038991, A038993, A038994, A038995, A038996, A038997, A038998, A038999. Sequence in context: A158558 A160893 A202994 * A068021 A131992 A042884 Adjacent sequences:  A038989 A038990 A038991 * A038993 A038994 A038995 KEYWORD nonn,mult AUTHOR EXTENSIONS Offset changed from 0 to 1 by R. J. Mathar, Mar 31 2011 More terms from Joerg Arndt, Oct 07 2012 STATUS approved

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Last modified January 20 16:32 EST 2022. Contains 350472 sequences. (Running on oeis4.)