0,2

a(n) must be chosen so its rightmost digit is not 8 (so that the next term won't start with 0). - Sam Alexander (amnalexander(AT)yahoo.com), Jan 04 2005

If n>=20, then a(n) is a(n-16) with one period 24680 (or a suitable cyclic permutatin thereof) appended (or prepended, or inserted, whatever one prefers). [From Hagen von Eitzen (math(AT)von-eitzen.de), Jun 18 2009]

Let (c[0], c[1], ..., c[15]) = (8024600, 2468000, 68024000, 24680000, 80246000, 4680200, 802460000, 680240000, 468020000, 2468000000, 24680000000, 4680200000, 46802000000, 6802400000,68024000000,8024600000), i.e. c[r] = a[r+20] - a[r+4] for 0 <= r < 16. If n>=4, then writing n = 16*k + r + 4 with 0<=r<16 we have a(n) = floor( c[r]*100000^k/99999 ). [From Hagen von Eitzen (math(AT)von-eitzen.de), Jun 18 2009]

G.f.: -4 + 2 x - 2 x^2 + 6 x^3 + (4 + 6 x^2 + 80 x^4 + 24 x^5 + 680 x^6 + 246 x^7 + 802 x^8 + 46 x^9 + 8024 x^10 + 6802 x^11 + 4680 x^12 + 24680 x^13 + 246802 x^14 + 46802 x^15 + 68020 x^16 + 68024 x^17 + 80240 x^18 + 80246 x^19 + 24600 x^20 + 68000 x^21 + 24000 x^22 + 80000 x^23 + 46000 x^24 + 80200 x^25 + 60000 x^26 + 40000 x^27 + 20000 x^28 - 200000 x^30)/(1 - 100001 x^16 + 100000 x^32) [From Hagen von Eitzen (math(AT)von-eitzen.de), Jul 19 2009]

Sequence in context: A084324 A066220 A009257 this_sequence A056012 A066719 A033319

Adjacent sequences: A098754 A098755 A098756 this_sequence A098758 A098759 A098760

base,easy,nonn

Eric Angelini (eric.angelini(AT)kntv.be), Oct 01 2004

More terms from Sam Alexander (amnalexander(AT)yahoo.com), Jan 04 2005

More terms from Hagen von Eitzen (math(AT)von-eitzen.de), Jun 18 2009