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A337307 revision #15

A337307

a(1) = 1; a(n) = 1 + Product_{k=1..n-1} a(k) (mod n-1).

1, 1, 2, 3, 3, 4, 1, 3, 1, 1, 7, 6, 1, 12, 1, 10, 1, 12, 1, 3, 1, 1, 21, 12, 1, 6, 21, 1, 1, 15, 1, 20, 1, 31, 15, 1, 1, 32, 13, 1, 1, 18, 1, 7, 25, 1, 17, 38, 1, 1, 1, 1, 1, 26, 1, 6, 1, 1, 29, 47, 1, 42, 1, 1, 1, 1, 61, 26, 1, 25, 1, 21, 1, 64, 21, 1, 1, 29, 1, 18

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,3

COMMENTS

Note that the running product for each a(n) is incrementally computed mod n-1.

LINKS

Table of n, a(n) for n=1..80.

MATHEMATICA

a[1] = 1; a[n_] := a[n] = 1 + Mod[Product[a[k], {k, 1, n - 1}], n - 1]; Array[a, 100] (* Amiram Eldar, Aug 22 2020 *)

PROG

(Python)

def f(n):

if n == 1: return 1

a = 1

for k in range(1, n):

a = a * f(k) % (n - 1)

return a + 1

(PARI) lista(nn) = {my(va = vector(nn)); va[1] = 1; for (n=2, nn, va[n] = 1 + prod(k=1, n-1, va[k]) % (n-1); ); va; } \\ Michel Marcus, Aug 23 2020

CROSSREFS

Inspired by A066910.

Cf. A129871 (without the mod operation).

Sequence in context: A285891 A060573 A279086 * A357372 A316910 A251715

Adjacent sequences: A337304 A337305 A337306 * A337308 A337309 A337310

KEYWORD

nonn

AUTHOR

Matt Donahoe, Aug 22 2020

STATUS

approved