A220986 The right Aurifeuillian factor of 10^(20n + 10) + 1.

27961, 1105207205101, 101005020070200501001, 10010005002000700200050010001, 1000100005000200007000200005000100001, 100001000005000020000070000200000500001000001, 10000010000005000002000000700000200000050000010000001

Offset

0,1

Comments

The corresponding left Aurifeuillian factor is A220985.

Links

Table of n, a(n) for n=0..6.

Wikipedia, Cunningham Project

Formula

a(n) = 10^(8n + 4) + 10^(7n + 4) + 5 * 10^(6n + 3) + 2 * 10^(5n + 3) + 7 * 10^(4n + 2) + 2 * 10^(3n + 2) + 5 * 10^(2n + 1) + 10^(n + 1) + 1

Aurifeuillian factorization: 10^(20n + 10) + 1 = (10^(4n + 2) + 1) * A220985(n) * a(n)

Mathematica

a[n_] := 10^(8n + 4) + 10^(7n + 4) + 5 * 10^(6n + 3) + 2 * 10^(5n + 3) + 7 * 10^(4n + 2) + 2 * 10^(3n + 2) + 5 * 10^(2n + 1) + 10^(n + 1) + 1

Crossrefs

Cf. A092440, A085601, A220978, A198410, A220979, A220980, A220981, A220982

Cf. A220983, A220984, A220985, A220987, A220988, A220989, A220990

Sequence in context: A206618 A363168 A233430 * A242607 A203658 A247992

Adjacent sequences: A220983 A220984 A220985 * A220987 A220988 A220989

Keyword

nonn,easy

Author

Stuart Clary, Dec 27 2012

Status

approved