|
Search: id:A101278
|
|
|
| A101278 |
|
Write n in base 3 as n = b_0 + b_1*3 + b_2*3^2 + b_3*3^3 + ...; then a(n) = Product_{i >= 0} prime(i+1)^b_i. |
|
+0
1
|
|
| 1, 2, 4, 3, 6, 12, 9, 18, 36, 5, 10, 20, 15, 30, 60, 45, 90, 180, 25, 50, 100, 75, 150, 300, 225, 450, 900, 7, 14, 28, 21, 42, 84, 63, 126, 252, 35, 70, 140, 105, 210, 420, 315, 630, 1260, 175, 350, 700, 525, 1050, 2100, 1575, 3150, 6300, 49, 98, 196, 147, 294, 588
(list; graph; listen)
|
|
|
OFFSET
|
0,2
|
|
|
COMMENT
|
One may generate other sequences by changing the base b.
|
|
FORMULA
|
If a(bn)=x then a(bn+1)=2x, a(bn+2)=4x, ... a(bn+b-1)=2^b*x. - Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 24 2004
G.f.: (1+2x+4x^2)(1+3x^3+9x^6)(1+5x^9+25x^18)... - Paul Boddington (psb(AT)maths.warwick.ac.uk), Jul 21 2005
|
|
EXAMPLE
|
The first few terms are computed as follows:
n b2 b1 b0 a(n)
0, 0, 0, 0, 1
1, 0, 0, 1, 2
2, 0, 0, 2, 4
3, 0, 1, 0, 3
4, 0, 1, 1, 6
5, 0, 1, 2, 12
|
|
MATHEMATICA
|
primeBase[n_Integer?Positive, base_Integer]/; base>1 := Times @@ (Table[Prime[i], {i, Floor[Log[base, n] + 1], 1, -1}]^IntegerDigits[n, base]); Table[primeBase[n, 3], {n, 59}] (from Robert G. Wilson v Dec 24 2004)
|
|
CROSSREFS
|
Sequence in context: A134561 A120947 A046793 this_sequence A091274 A122525 A054589
Adjacent sequences: A101275 A101276 A101277 this_sequence A101279 A101280 A101281
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
Orges Leka (oleka(AT)students.uni-mainz.de), Dec 20 2004
|
|
EXTENSIONS
|
More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 24 2004
|
|
|
Search completed in 0.002 seconds
|
