A348135
Irregular triangle T(n, k), n > 0, k = 1..A067399(n), read by rows; the n-th row gives, in ascending order, the distinct integers k such that A067138(k, m) = n for some m.
Original entry on oeis.org
1, 1, 2, 1, 3, 1, 2, 4, 1, 5, 1, 2, 3, 6, 1, 3, 7, 1, 2, 4, 8, 1, 9, 1, 2, 5, 10, 1, 11, 1, 2, 3, 4, 6, 12, 1, 13, 1, 2, 3, 6, 7, 14, 1, 3, 5, 7, 15, 1, 2, 4, 8, 16, 1, 17, 1, 2, 9, 18, 1, 19, 1, 2, 4, 5, 10, 20, 1, 5, 21, 1, 2, 11, 22, 1, 23, 1, 2, 3, 4, 6, 8, 12, 24
Offset: 1
The triangle starts:
1: [1]
2: [1, 2]
3: [1, 3]
4: [1, 2, 4]
5: [1, 5]
6: [1, 2, 3, 6]
7: [1, 3, 7]
8: [1, 2, 4, 8]
9: [1, 9]
10: [1, 2, 5, 10]
11: [1, 11]
12: [1, 2, 3, 4, 6, 12]
13: [1, 13]
14: [1, 2, 3, 6, 7, 14]
15: [1, 3, 5, 7, 15]
16: [1, 2, 4, 8, 16]
A190376
a(n) = sum (in ordinary arithmetic) of A067399(k), for k from 2^n to 2^(n+1)-1.
Original entry on oeis.org
1, 4, 12, 31, 75, 175, 393, 864, 1868, 3978, 8394
Offset: 0
-
read("transforms");
numbralADD := proc(a,b) option remember; ORnos(a,b) ; end proc:
numbralMUL := proc(a,b) option remember; local p,bshf,s ; p := 0 ; bshf := b ; for s from 0 do if bshf mod 2 <> 0 then p := numbralADD(p, 2^s*a ) ; end if; bshf := floor(bshf/2) ; if bshf = 0 then return p; end if; end do; end proc:
isnumbralDiv := proc(n,d) option remember; for e from 0 do if numbralMUL(e,d) = n then return true; elif numbralMUL(e,d) > 2*n then return false; end if; end do: end proc:
numbralDivisors := proc(n) option remember; local d,i; d := {} ; for i from 1 to n do if isnumbralDiv(n,i) then d := d union {i} ; end if; end do: d ; end proc:
A067399 := proc(n) nops(numbralDivisors(n)) ; end proc:
A190376 := proc(n) add(A067399(k),k=2^n..2^(n+1)-1) ; end proc: # R. J. Mathar, May 30 2011
A079500
Number of compositions of the integer n in which the first part is >= the other parts.
Original entry on oeis.org
1, 1, 2, 3, 5, 8, 14, 24, 43, 77, 140, 256, 472, 874, 1628, 3045, 5719, 10780, 20388, 38674, 73562, 140268, 268066, 513350, 984911, 1892875, 3643570, 7023562, 13557020, 26200182, 50691978, 98182666, 190353370, 369393466, 717457656, 1394632365, 2713061899
Offset: 0
From _Joerg Arndt_, Dec 29 2012: (Start)
There are a(7)=24 compositions p(1)+p(2)+...+p(m)=7 such that p(k) <= p(1):
[ 1] [ 1 1 1 1 1 1 1 ]
[ 2] [ 2 1 1 1 1 1 ]
[ 3] [ 2 1 1 1 2 ]
[ 4] [ 2 1 1 2 1 ]
[ 5] [ 2 1 2 1 1 ]
[ 6] [ 2 1 2 2 ]
[ 7] [ 2 2 1 1 1 ]
[ 8] [ 2 2 1 2 ]
[ 9] [ 2 2 2 1 ]
[10] [ 3 1 1 1 1 ]
[11] [ 3 1 1 2 ]
[12] [ 3 1 2 1 ]
[13] [ 3 1 3 ]
[14] [ 3 2 1 1 ]
[15] [ 3 2 2 ]
[16] [ 3 3 1 ]
[17] [ 4 1 1 1 ]
[18] [ 4 1 2 ]
[19] [ 4 2 1 ]
[20] [ 4 3 ]
[21] [ 5 1 1 ]
[22] [ 5 2 ]
[23] [ 6 1 ]
[24] [ 7 ]
(End)
From _Joerg Arndt_, Jul 20 2014: (Start)
The a(7) = 24 balanced ordered rooted trees with 7 non-root nodes are, as level sequences (of the pre-order walk):
01: [ 0 1 1 1 1 1 1 1 ]
02: [ 0 1 2 1 2 1 2 2 ]
03: [ 0 1 2 1 2 2 1 2 ]
04: [ 0 1 2 1 2 2 2 2 ]
05: [ 0 1 2 2 1 2 1 2 ]
06: [ 0 1 2 2 1 2 2 2 ]
07: [ 0 1 2 2 2 1 2 2 ]
08: [ 0 1 2 2 2 2 1 2 ]
09: [ 0 1 2 2 2 2 2 2 ]
10: [ 0 1 2 3 1 2 3 3 ]
11: [ 0 1 2 3 2 3 2 3 ]
12: [ 0 1 2 3 2 3 3 3 ]
13: [ 0 1 2 3 3 1 2 3 ]
14: [ 0 1 2 3 3 2 3 3 ]
15: [ 0 1 2 3 3 3 2 3 ]
16: [ 0 1 2 3 3 3 3 3 ]
17: [ 0 1 2 3 4 2 3 4 ]
18: [ 0 1 2 3 4 3 4 4 ]
19: [ 0 1 2 3 4 4 3 4 ]
20: [ 0 1 2 3 4 4 4 4 ]
21: [ 0 1 2 3 4 5 4 5 ]
22: [ 0 1 2 3 4 5 5 5 ]
23: [ 0 1 2 3 4 5 6 6 ]
24: [ 0 1 2 3 4 5 6 7 ]
(End)
From _Gus Wiseman_, Oct 07 2018: (Start)
The a(0) = 1 through a(6) = 14 balanced rooted plane trees:
o (o) (oo) (ooo) (oooo) (ooooo) (oooooo)
((o)) ((oo)) ((ooo)) ((oooo)) ((ooooo))
(((o))) (((oo))) (((ooo))) (((oooo)))
((o)(o)) ((o)(oo)) ((o)(ooo))
((((o)))) ((oo)(o)) ((oo)(oo))
((((oo)))) ((ooo)(o))
(((o)(o))) ((((ooo))))
(((((o))))) (((o)(oo)))
(((oo)(o)))
((o)(o)(o))
(((((oo)))))
((((o)(o))))
(((o))((o)))
((((((o))))))
(End)
- Arnold Knopfmacher and Neville Robbins, Compositions with parts constrained by the leading summand, Ars Combin. 76 (2005), 287-295.
- Alois P. Heinz, Table of n, a(n) for n = 0..2000 (first 400 terms from T. D. Noe)
- D. Applegate, M. LeBrun and N. J. A. Sloane, Dismal Arithmetic, arXiv:1107.1130 [math.NT], 2011. [Note: we have now changed the name from "dismal arithmetic" to "lunar arithmetic" - the old name was too depressing]
- D. Applegate, M. LeBrun, N. J. A. Sloane, Dismal Arithmetic, J. Int. Seq. 14 (2011) # 11.9.8.
- Srecko Brlek, Andrea Frosini, Simone Rinaldi, and Laurent Vuillon, Tilings by translation: enumeration by a rational language approach, The Electronic Journal of Combinatorics, vol.13, (2006).
- A. Frosini and S. Rinaldi, On the Sequence A079500 and Its Combinatorial Interpretations, Journal of Integer Sequences, Vol. 9 (2006), Article 06.3.1.
- R. Kemp, Balanced ordered trees, Random Structures Algorithms, 5 (1994), pp. 99-121.
- Index entries for sequences related to dismal (or lunar) arithmetic
-
M:=101:
t1:=add( (1-x)*x^k/(1-2*x+x^k), k=1..M):
series(t1,x,M-1);
seriestolist(%);
# second Maple program:
b:= proc(n, m) option remember; `if`(n=0, 1,
`if`(m=0, add(b(n-j, j), j=1..n),
add(b(n-j, min(n-j, m)), j=1..min(n, m))))
end:
a:= n-> b(n, 0):
seq(a(n), n=0..40); # Alois P. Heinz, May 01 2014
-
nn=36;CoefficientList[Series[Sum[x^i/(1-(x-x^(i+1))/(1-x)),{i,0,nn}],{x,0,nn}],x] (* Geoffrey Critzer, Mar 12 2013 *)
b[n_, m_] := b[n, m] = If[n==0, 1, If[m==0, Sum[b[n-j, j], {j, 1, n}], Sum[ b[n-j, Min[n-j, m]], {j, 1, Min[n, m]}]]]; a[n_] := b[n, 0]; Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Nov 23 2015, after Alois P. Heinz *)
Further edits (required in order to clarify the definition - is the first part >= the rest. or only > the rest? Answer: the former; for the latter, see
A007059) by
N. J. A. Sloane, May 08 2011
A087029
Number of lunar divisors of n (unbounded version).
Original entry on oeis.org
9, 8, 7, 6, 5, 4, 3, 2, 1, 18, 90, 16, 14, 12, 10, 8, 6, 4, 2, 16, 16, 72, 14, 12, 10, 8, 6, 4, 2, 14, 14, 14, 56, 12, 10, 8, 6, 4, 2, 12, 12, 12, 12, 42, 10, 8, 6, 4, 2, 10, 10, 10, 10, 10, 30, 8, 6, 4, 2, 8, 8, 8, 8, 8, 8, 20, 6, 4, 2, 6, 6, 6, 6, 6, 6, 6, 12, 4, 2, 4, 4, 4, 4
Offset: 1
The 18 divisors of 10 are 1, 2, ..., 9, 10, 20, 30, ..., 90, so a(10) = 18.
- D. Applegate, Table of n, a(n) for n = 1..100000
- D. Applegate, C program for lunar arithmetic and number theory
- D. Applegate, M. LeBrun and N. J. A. Sloane, Dismal Arithmetic, arxiv:1107.1130 [math-NT], July 2011. [Note: we have now changed the name from "dismal arithmetic" to "lunar arithmetic" - the old name was too depressing]
- D. Applegate, M. LeBrun, N. J. A. Sloane, Dismal Arithmetic, J. Int. Seq. 14 (2011) # 11.9.8.
- Brady Haran and N. J. A. Sloane, Primes on the Moon (Lunar Arithmetic), Numberphile video, Nov 2018.
- Index entries for sequences related to dismal (or lunar) arithmetic
See
A067399 for the base-2 version.
-
(Uses programs from A087062. This crude program is valid for n <= 99.) dd2 := proc(n) local t1,t2,i,j; t1 := []; for i from 1 to 99 do for j from i to 99 do if dmul(i,j) = n then t1 := [op(t1),i,j]; fi; od; od; t1 := convert(t1,set); t2 := sort(convert(t1,list)); nops(t2); end;
-
A087029(n)=#A189506_row(n) \\ To be optimized. - M. F. Hasler, Nov 15 2018
A067398
Squares in OR-numbral arithmetic.
Original entry on oeis.org
0, 1, 4, 7, 16, 21, 28, 31, 64, 73, 84, 95, 112, 125, 124, 127, 256, 273, 292, 311, 336, 341, 380, 383, 448, 473, 500, 511, 496, 509, 508, 511, 1024, 1057, 1092, 1127, 1168, 1205, 1244, 1279, 1344, 1385, 1364, 1407, 1520, 1533, 1532, 1535, 1792, 1841, 1892
Offset: 0
A067398(5) = 21 since [5] * [5] = [21] in OR-numbral arithmetic.
- Reinhard Zumkeller, Table of n, a(n) for n = 0..10000
- D. Applegate, M. LeBrun and N. J. A. Sloane, Dismal Arithmetic [Note: we have now changed the name from "dismal arithmetic" to "lunar arithmetic" - the old name was too depressing]
- D. Applegate, M. LeBrun, N. J. A. Sloane, Dismal Arithmetic, J. Int. Seq. 14 (2011) # 11.9.8.
- A. Frosini and S. Rinaldi, On the Sequence A079500 and Its Combinatorial Interpretations, J. Integer Seq., Vol. 9 (2006), Article 06.3.1.
- Index entries for sequences related to dismal (or lunar) arithmetic
A188548
The sum of the divisors of n in base-2 lunar arithmetic.
Original entry on oeis.org
1, 11, 11, 111, 101, 111, 111, 1111, 1001, 1111, 1011, 1111, 1101, 1111, 1111, 11111, 10001, 11011, 10011, 11111, 10101, 11111, 10111, 11111, 11001, 11111, 11011, 11111, 11101, 11111, 11111, 111111, 100001, 110011, 100011, 111111, 100101, 110111, 100111, 111111, 101001, 111111, 101011, 111111, 101101, 111111, 101111, 111111, 110001, 111011, 110011, 111111
Offset: 1
The 4th binary number is 100 which has lunar divisors 1, 10, 100, whose lunar sum is 111, so a(4)=111.
The 5th binary number is 101 which has lunar divisors 1 and 101, whose lunar sum is 101, so a(5)=101.
It might be tempting to conjecture that if n is even then a(n) = 111...111, but a(18)=11011 shows that this is false (see A190149).
A067400
Non-uniquely factorizable OR-numbrals, i.e., numbrals for which there exist more than one different factorizations into irreducible factors (modulo order).
Original entry on oeis.org
15, 30, 31, 60, 62, 63, 85, 95, 111, 120, 123, 124, 125, 126, 127, 170, 175, 190, 191, 207, 222, 223, 239, 240, 243, 245, 246, 247, 248, 250, 251, 252, 253, 254, 255, 340, 341, 350, 351, 367, 379, 380, 381, 382, 383, 399, 414, 415, 443, 444, 445, 446, 447
Offset: 1
15 is in A067400 since [15] = [3] * [5] = [3]^3 and [3] and [5] are irreducible.
A067401
Minimal non-uniquely factorizable OR-numbrals, i.e., numbrals that are not uniquely factorizable but for which all proper divisors are.
Original entry on oeis.org
15, 85, 95, 111, 123, 125, 175, 191, 207, 223, 239, 243, 245, 247, 251, 253, 351, 367, 379, 381, 399, 415, 443, 445, 447, 463, 483, 487, 493, 499, 501, 507, 585, 603, 621, 631, 639, 685, 687, 701, 725, 729, 731, 735, 757, 763, 783, 799, 827, 831, 873, 877
Offset: 1
15 is in A067401 since [15] = [3] * [5] = [3]^3 all divisors of [15] are uniquely factorizable.
A190149
Even numbers n (written in binary) such that in base-2 lunar arithmetic, the sum of the divisors of n is a number containing a 0 (in binary).
Original entry on oeis.org
10010, 100010, 100110, 110010, 1000010, 1000100, 1000110, 1001010, 1001110, 1010010, 1100010, 1100110, 1110010, 10000010, 10000100, 10000110, 10001010, 10001100, 10001110, 10010010, 10010110, 10011010, 10011110, 10100010, 10100110, 10110010, 11000010, 11000100, 11000110, 11001010, 11001110, 11010010, 11100010, 11100110, 11110010, 100000010, 100000100
Offset: 1
In base-2 lunar arithmetic, the divisors of 10010 are 1, 10, 1001 and 10010, whose sum is 11011.
A187141
Number of lunar divisors of n in base 3.
Original entry on oeis.org
2, 1, 4, 6, 2, 2, 2, 2, 6, 6, 2, 12, 14, 3, 4, 4, 4, 3, 2, 2, 4, 3, 2, 4, 4, 3, 8, 6, 2, 12, 10, 2, 4, 2, 2, 18, 10, 2, 28, 34, 5, 6, 7, 7, 6, 2, 2, 8, 7, 5, 8, 8, 6, 4, 2, 2, 4, 2, 2, 4, 2, 2, 6, 2, 2, 6, 5, 2, 4, 5, 2, 6, 2, 2, 8, 7, 2, 6, 6, 6, 10, 6, 2, 12, 10, 2, 4, 2, 2, 18, 14, 3, 20, 18, 2, 4, 2, 2, 6, 4, 4, 4, 2, 2, 4, 2, 2, 24, 10, 2, 20, 26, 4, 4, 4, 4, 42, 18, 2, 68
Offset: 1
If written as a triangle, with rows of length 2*3^i:
2, 1,
4, 6, 2, 2, 2, 2,
6, 6, 2, 12, 14, 3, 4, 4, 4, 3, 2, 2, 4, 3, 2, 4, 4, 3,
8, 6, 2, 12, 10, 2, 4, 2, 2, 18, 10, 2, 28, 34, 5, 6, 7, 7, 6, 2, 2, 8, 7, 5, 8, 8, 6, 4, 2, 2, 4, 2, 2, 4, 2, 2, 6, 2, 2, 6, 5, 2, 4, 5, 2, 6, 2, 2, 8, 7, 2, 6, 6, 6,
10, 6, 2, 12, 10, 2, 4, 2, 2, 18, 14, 3, 20, 18, 2, 4, 2, 2, 6, 4, 4, 4, 2, 2, 4, 2, 2, 24, 10, 2, 20, 26, 4, 4, 4, 4, 42, 18, 2, 6, ...
Showing 1-10 of 10 results.
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