A220985 The left Aurifeuillian factor of 10^(20n+10) + 1.

3541, 904806804901, 99004980069800499001, 9990004998000699800049990001, 999900004999800006999800004999900001, 99999000004999980000069999800000499999000001, 9999990000004999998000000699999800000049999990000001

Offset

0,1

Comments

The corresponding right Aurifeuillian factor is A220986.

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) * a(n) * A220986(n).

Mathematica

Table[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, {n, 0, 20}]

Crossrefs

Cf. A092440, A085601, A220978, A198410, A220979-A220990.

Sequence in context: A176139 A354542 A020412 * A252989 A253309 A253657

Adjacent sequences: A220982 A220983 A220984 * A220986 A220987 A220988

Keyword

nonn,easy

Author

Stuart Clary, Dec 27 2012

Status

approved