A047215 -id:A047215 - cp's OEIS frontend

A191740 Dispersion of A047220, (numbers >1 and congruent to 0 or 1 or 3 mod 5), by antidiagonals.

1, 3, 2, 6, 5, 4, 11, 10, 8, 7, 20, 18, 15, 13, 9, 35, 31, 26, 23, 16, 12, 60, 53, 45, 40, 28, 21, 14, 101, 90, 76, 68, 48, 36, 25, 17, 170, 151, 128, 115, 81, 61, 43, 30, 19, 285, 253, 215, 193, 136, 103, 73, 51, 33, 22, 476, 423, 360, 323, 228, 173, 123

Offset: 1

Clark Kimberling, Jun 14 2011

For a background discussion of dispersions and their fractal sequences, see A191426.  For dispersions of congruence sequences mod 3, mod 4, or mod 5, see A191655, A191663, A191667, A191702.
...
Suppose that {2,3,4,5,6} is partitioned as {x1, x2} and {x3,x4,x5}.  Let S be the increasing sequence of numbers >1 and congruent to x1 or x2 mod 5, and let T be the increasing sequence of numbers >1 and congruent to x3 or x4 or x5 mod 5.  There are 10 sequences in S, each matched by a (nearly) complementary sequence in T.  Each of the 20 sequences generates a dispersion, as listed here:
...
A191722=dispersion of A008851 (0, 1 mod 5 and >1)
A191723=dispersion of A047215 (0, 2 mod 5 and >1)
A191724=dispersion of A047218 (0, 3 mod 5 and >1)
A191725=dispersion of A047208 (0, 4 mod 5 and >1)
A191726=dispersion of A047216 (1, 2 mod 5 and >1)
A191727=dispersion of A047219 (1, 3 mod 5 and >1)
A191728=dispersion of A047209 (1, 4 mod 5 and >1)
A191729=dispersion of A047221 (2, 3 mod 5 and >1)
A191730=dispersion of A047211 (2, 4 mod 5 and >1)
A191731=dispersion of A047204 (3, 4 mod 5 and >1)
...
A191732=dispersion of A047202 (2,3,4 mod 5 and >1)
A191733=dispersion of A047206 (1,3,4 mod 5 and >1)
A191734=dispersion of A032793 (1,2,4 mod 5 and >1)
A191735=dispersion of A047223 (1,2,3 mod 5 and >1)
A191736=dispersion of A047205 (0,3,4 mod 5 and >1)
A191737=dispersion of A047212 (0,2,4 mod 5 and >1)
A191738=dispersion of A047222 (0,2,3 mod 5 and >1)
A191739=dispersion of A008854 (0,1,4 mod 5 and >1)
A191740=dispersion of A047220 (0,1,3 mod 5 and >1)
A191741=dispersion of A047217 (0,1,2 mod 5 and >1)
...
For further information about these 20 dispersions, see A191722.
...
Regarding the dispersions A191722-A191741, there are general formulas for sequences of the type "(a or b mod m)" and "(a or b or c mod m)" used in the relevant Mathematica programs.

			Northwest corner:
1....3....6....11...20
2....5....10...18...31
4....8....15...26...45
7....13...23...40...68
9....16...28...48...81
12...21...36...61...103

Ivan Neretin, Table of n, a(n) for n = 1..5050 (first 100 antidiagonals, flattened)

Cf. A047211, A047220, A191722, A191730, A191426.

(* Program generates the dispersion array t of the increasing sequence f[n] *)
r = 40; r1 = 12;  c = 40; c1 = 12;
a=3; b=5; c2=6; m[n_]:=If[Mod[n,3]==0,1,0];
f[n_]:=a*m[n+2]+b*m[n+1]+c2*m[n]+5*Floor[(n-1)/3]
Table[f[n], {n, 1, 30}]  (* A047220 *)
mex[list_] := NestWhile[#1 + 1 &, 1, Union[list][[#1]] <= #1 &, 1, Length[Union[list]]]
rows = {NestList[f, 1, c]};
Do[rows = Append[rows, NestList[f, mex[Flatten[rows]], r]], {r}];
t[i_, j_] := rows[[i, j]];
TableForm[Table[t[i, j], {i, 1, 10}, {j, 1, 10}]]
  (* A191740 *)
Flatten[Table[t[k, n - k + 1], {n, 1, c1}, {k, 1, n}]] (* A191740  *)

A191741 Dispersion of A047217, (numbers >1 and congruent to 0 or 1 or 2 mod 5), by antidiagonals.

Original entry on oeis.org

1, 2, 3, 5, 6, 4, 10, 11, 7, 8, 17, 20, 12, 15, 9, 30, 35, 21, 26, 16, 13, 51, 60, 36, 45, 27, 22, 14, 86, 101, 61, 76, 46, 37, 25, 18, 145, 170, 102, 127, 77, 62, 42, 31, 19, 242, 285, 171, 212, 130, 105, 71, 52, 32, 23, 405, 476, 286, 355, 217, 176, 120

Offset: 1

Clark Kimberling, Jun 14 2011

For a background discussion of dispersions and their fractal sequences, see A191426.  For dispersions of congruence sequences mod 3, mod 4, or mod 5, see A191655, A191663, A191667, A191702.
...
Suppose that {2,3,4,5,6} is partitioned as {x1, x2} and {x3,x4,x5}.  Let S be the increasing sequence of numbers >1 and congruent to x1 or x2 mod 5, and let T be the increasing sequence of numbers >1 and congruent to x3 or x4 or x5 mod 5.  There are 10 sequences in S, each matched by a (nearly) complementary sequence in T.  Each of the 20 sequences generates a dispersion, as listed here:
...
A191722=dispersion of A008851 (0, 1 mod 5 and >1)
A191723=dispersion of A047215 (0, 2 mod 5 and >1)
A191724=dispersion of A047218 (0, 3 mod 5 and >1)
A191725=dispersion of A047208 (0, 4 mod 5 and >1)
A191726=dispersion of A047216 (1, 2 mod 5 and >1)
A191727=dispersion of A047219 (1, 3 mod 5 and >1)
A191728=dispersion of A047209 (1, 4 mod 5 and >1)
A191729=dispersion of A047221 (2, 3 mod 5 and >1)
A191730=dispersion of A047211 (2, 4 mod 5 and >1)
A191731=dispersion of A047204 (3, 4 mod 5 and >1)
...
A191732=dispersion of A047202 (2,3,4 mod 5 and >1)
A191733=dispersion of A047206 (1,3,4 mod 5 and >1)
A191734=dispersion of A032793 (1,2,4 mod 5 and >1)
A191735=dispersion of A047223 (1,2,3 mod 5 and >1)
A191736=dispersion of A047205 (0,3,4 mod 5 and >1)
A191737=dispersion of A047212 (0,2,4 mod 5 and >1)
A191738=dispersion of A047222 (0,2,3 mod 5 and >1)
A191739=dispersion of A008854 (0,1,4 mod 5 and >1)
A191740=dispersion of A047220 (0,1,3 mod 5 and >1)
A191741=dispersion of A047217 (0,1,2 mod 5 and >1)
...
For further information about these 20 dispersions, see A191722.
...
Regarding the dispersions A191722-A191741, there are general formulas for sequences of the type "(a or b mod m)" and "(a or b or c mod m)" used in the relevant Mathematica programs.

			Northwest corner:
1....2....5....10...17
3....6....11...20...35
4....7....12...21...36
8....15...26...45...76
9....16...27...46...77
13...22...37...62...105

Ivan Neretin, Table of n, a(n) for n = 1..5050 (first 100 antidiagonals, flattened)

Cf. A047204, A047217, A191722, A191731, A191426.

(* Program generates the dispersion array t of the increasing sequence f[n] *)
r = 40; r1 = 12;  c = 40; c1 = 12;
a=2; b=5; c2=6; m[n_]:=If[Mod[n,3]==0,1,0];
f[n_]:=a*m[n+2]+b*m[n+1]+c2*m[n]+5*Floor[(n-1)/3]
Table[f[n], {n, 1, 30}]  (* A047217 *)
mex[list_] := NestWhile[#1 + 1 &, 1, Union[list][[#1]] <= #1 &, 1, Length[Union[list]]]
rows = {NestList[f, 1, c]};
Do[rows = Append[rows, NestList[f, mex[Flatten[rows]], r]], {r}];
t[i_, j_] := rows[[i, j]];
TableForm[Table[t[i, j], {i, 1, 10}, {j, 1, 10}]] (* A191741 *)
Flatten[Table[t[k, n - k + 1], {n, 1, c1}, {k, 1, n}]] (* A191741  *)

A301568 Expansion of Product_{k>=1} (1 + x^(5k))(1 + x^(5*k-3)).

Original entry on oeis.org

1, 0, 1, 0, 0, 1, 0, 2, 0, 1, 1, 0, 3, 0, 2, 2, 0, 5, 0, 4, 2, 1, 7, 0, 7, 3, 2, 10, 0, 11, 4, 4, 14, 0, 17, 5, 8, 19, 1, 25, 6, 13, 25, 2, 36, 8, 21, 33, 4, 50, 10, 33, 43, 8, 69, 12, 49, 55, 14, 93, 16, 71, 70, 23, 124, 20, 102, 88, 37, 163, 26, 142, 110, 57, 212

Offset: 0

Ilya Gutkovskiy, Mar 23 2018

nonn

Number of partitions of n into distinct parts congruent to 0 or 2 mod 5.

			a(12) = 3 because we have [12], [10, 2] and [7, 5].

Index entries for sequences related to partitions

Cf. A035368, A036822, A047215, A203776, A219607, A281272, A301562, A301563, A301564, A301565, A301567, A301569, A301570.

nmax = 74; CoefficientList[Series[Product[(1 + x^(5 k)) (1 + x^(5 k - 3)), {k, 1, nmax}], {x, 0, nmax}], x]
nmax = 74; CoefficientList[Series[x^3 QPochhammer[-1, x^5] QPochhammer[-x^(-3), x^5]/(2 (1 + x) (1 - x + x^2)), {x, 0, nmax}], x]
nmax = 74; CoefficientList[Series[Product[(1 + Boole[MemberQ[{0, 2}, Mod[k, 5]]] x^k), {k, 1, nmax}], {x, 0, nmax}], x]

G.f.: Product_{k>=1} (1 + x^A047215(k)).

a(n) ~ exp(Pi*sqrt(2*n/15)) / (2^(33/20) * 15^(1/4) * n^(3/4)). - Vaclav Kotesovec, Mar 24 2018

A235089 a(n)*Pi is the total length of irregular spiral (center points: 2, 1, 3, 4) after n rotations.

Original entry on oeis.org

3, 10, 13, 20, 23, 30, 33, 40, 43, 50, 53, 60, 63, 70, 73, 80, 83, 90, 93, 100, 103, 110, 113, 120, 123, 130, 133, 140, 143, 150, 153, 160, 163, 170, 173, 180, 183, 190, 193, 200, 203, 210, 213, 220, 223, 230, 233, 240, 243, 250, 253, 260, 263, 270, 273, 280, 283, 290, 293, 300, 303, 310, 313, 320, 323, 330, 333

Offset: 1

Kival Ngaokrajang, Jan 03 2014

nonn

Let points 2, 1, 3 & 4 be placed on a straight line at intervals of 1 unit. At point 1 make a half unit circle then at point 2 make another half circle and maintain continuity of circumferences. Continue using this procedure at point 3, 4, 1, ... and so on. The form is non-expanded loop.
The alternative point order [2, 3, 1, 4] gives the same pattern with reflection, but the sequence will be 2*A047215(n). See illustration in links.
Conjecture: Numbers equivalent 0 or 3 modulo 10. - Ralf Stephan, Jan 13 2014

Kival Ngaokrajang, Illustration of initial terms

Cf. A014105*Pi (total spiral length, 2 inline center points). A234902*Pi, A234903*Pi, A234904*Pi (total spiral length, 3 inline center points).

Conjectured partial sums of A010705.

Conjecture: a(n) = -1+(-1)^n+5*n. a(n) = a(n-1)+a(n-2)-a(n-3). G.f.: x*(7*x+3) / ((x-1)^2*(x+1)). - Colin Barker, Jan 16 2014

A075325 Pair the natural numbers such that the m-th pair is (r, s) where r, s and s-r are the smallest numbers which have not occurred earlier and also are not equal to the difference of any earlier pair: (1, 3), (4, 9), (6, 13), (8, 18), (11, 23), (14, 29), (16, 33), (19, 39), (21, 43), (24, 49), (26, 53), (28, 58), ... Sequence gives first term of each pair.

Original entry on oeis.org

1, 4, 6, 8, 11, 14, 16, 19, 21, 24, 26, 28, 31, 34, 36, 38, 41, 44, 46, 48, 51, 54, 56, 59, 61, 64, 66, 68, 71, 74, 76, 79, 81, 84, 86, 88, 91, 94, 96, 99, 101, 104, 106, 108, 111, 114, 116, 118, 121, 124, 126, 128, 131, 134, 136, 139, 141, 144, 146, 148, 151, 154, 156

Offset: 1

Amarnath Murthy, Sep 16 2002

nonn

Most of the pairs are of the form (r,2r+1) except for the ones like a(4) = (8,18) and a(12) = (28,58) and (38,78) etc. which are of the form (r,2r +2).

			The first pair (1, 3) covers 1, 2, 3. The second pair is (4, 9) covering 4, 5, 9.

Clark Kimberling, Table of n, a(n) for n = 1..10000
Robbert Fokkink and Gandhar Joshi, Anti-recurrence sequences, arXiv:2506.13337 [math.NT], 2025. See p. 4.

Cf. A007814, A075326, A075327.

The sequence formed by listing the differences between the second and first elements of each pair is A047215.

(* Here, the offset for (a(n)) is 0. *)
z = 200;
mex[list_, start_] := (NestWhile[# + 1 &, start, MemberQ[list, #] &]);
a = {}; b = {}; c = {};
Do[AppendTo[a,
   mex[Flatten[{a, b, c}], If[Length[a] == 0, 1, Last[a]]]];
  AppendTo[b, mex[Flatten[{a, b, c}], Last[a]]];
  AppendTo[c, Last[a] + Last[b]], {z}];
Take[a, 100] (* A075325 *)
Take[b, 100] (* A047215 *)
Take[c, 100] (* A075326 *)
Grid[{Join[{"n"}, Range[0, 20]], Join[{"a(n)"}, Take[a, 21]],
  Join[{"b(n)"}, Take[b, 21]], Join[{"c(n)"}, Take[c, 21]]},
 Alignment -> ".",
 Dividers -> {{2 -> Red, -1 -> Blue}, {2 -> Red, -1 -> Blue}}]
(* Peter J. C. Moses, Apr 26 2018 *)

used = vector(500); i = 1; A = vector(80); B = A; C = A; for (n = 1, 80, while (used[i], i++); j = i + 1; while (used[j] || used [i + j], j++); A[n] = i; B[n] = i + j; C[n] = i + i + j; used[i] = 1; used[j] = 1; used[i + j] = 1); A \\ David Wasserman, Jan 16 2005

Let A(n) = A007814(n). Let B(n) = A(n) + 1 if A(n) < 2; B(n) = 0 if A(n)>=2 & A(n) is even; B(n) = 2 if A(n) >= 2 & A(n) is odd. Then a(n) = (5n+B(n)-4)/2. - John Chew (jjchew(AT)math.utoronto.ca), Jun 20 2006

More terms from David Wasserman, Jan 16 2005

A183575 a(n) = n - 1 + ceiling((n^2-2)/2); complement of A183574.

Original entry on oeis.org

0, 2, 6, 10, 16, 22, 30, 38, 48, 58, 70, 82, 96, 110, 126, 142, 160, 178, 198, 218, 240, 262, 286, 310, 336, 362, 390, 418, 448, 478, 510, 542, 576, 610, 646, 682, 720, 758, 798, 838, 880, 922, 966, 1010, 1056, 1102, 1150, 1198, 1248, 1298, 1350, 1402, 1456, 1510, 1566, 1622, 1680, 1738, 1798, 1858, 1920, 1982, 2046, 2110, 2176, 2242, 2310, 2378, 2448, 2518

Offset: 1

Clark Kimberling, Jan 05 2011

Agrees with the circumference of the n X n stacked book graph for n = 2 up to at least n = 8. - Eric W. Weisstein, Dec 05 2017

It seems that a(n-1) is the maximal length of an optimal solution path required to solve any n X n maze. Here the maze has a single start point, a single end point, and any number of walls that cannot be traversed. The maze is 4-connected, so the allowed moves are: up, down, left and right. For odd n, the hardest mazes have walls located in a spiral, start point in one corner and end point in the center. - Dmitry Kamenetsky, Mar 06 2018

Colin Barker, Table of n, a(n) for n = 1..1000
Eric Weisstein's World of Mathematics, Graph Circumference.
Eric Weisstein's World of Mathematics, Stacked Book Graph.
Index entries for linear recurrences with constant coefficients, signature (2,0,-2,1).

Cf. A183574 (complement).

Table[Ceiling[n^2/2 - 1] + n - 1, {n, 20}] (* Eric W. Weisstein, May 18 2017 *)
Table[(2 n (n + 2) - 7 - (-1)^n)/4, {n, 20}] (* Eric W. Weisstein, May 18 2017 *)
Table[If[Mod[n, 2] == 0, n^2 + 2 n - 4, (n + 3) (n - 1)]/2, {n, 20}] (* Eric W. Weisstein, May 18 2017 *)
LinearRecurrence[{2,0,-2,1},{0,2,6,10},80] (* Harvey P. Dale, Feb 19 2021 *)

concat(0, Vec(2*x*(1 + x - x^2) / ((1 - x)^3*(1 + x)) + O(x^60))) \\ Colin Barker, Dec 07 2017

a(n) = n - 1 + ceiling(n^2/2-1).
a(n) = A000217(n-2) + A047215(n-1). - Wesley Ivan Hurt, Jul 15 2013
From Colin Barker, Dec 07 2017: (Start)
G.f.: 2*x^2*(1 + x - x^2) / ((1 - x)^3*(1 + x)).
a(n) = (n^2 + 2*n - 4)/2 for n even.
a(n) = (n^2 + 2*n - 3)/2 for n odd.
a(n) = 2*a(n-1) - 2*a(n-3) + a(n-4) for n > 4.
(End)
Sum_{n>=2} 1/a(n) = 7/8 + tan(sqrt(5)*Pi/2)*Pi/(2*sqrt(5)). - Amiram Eldar, Sep 16 2022
E.g.f.: (4 + (x^2 + 3*x - 4)*cosh(x) + (x^2 + 3*x - 3)*sinh(x))/2. - Stefano Spezia, Sep 05 2023

Description corrected by Eric W. Weisstein, May 18 2017

a(1)=0 inserted by Amiram Eldar, Sep 16 2022

A256680 Minimal most likely sum for a roll of n 4-sided dice.

Original entry on oeis.org

0, 1, 5, 7, 10, 12, 15, 17, 20, 22, 25, 27, 30, 32, 35, 37, 40, 42, 45, 47, 50, 52, 55, 57, 60, 62, 65, 67, 70, 72, 75, 77, 80, 82, 85, 87, 90, 92, 95, 97, 100, 102, 105, 107, 110, 112, 115, 117, 120, 122, 125, 127, 130, 132, 135, 137, 140, 142, 145, 147, 150, 152, 155, 157, 160, 162

Offset: 0

Ran Pan, Apr 08 2015

In fact ceiling(5n/2) and floor(5n/2) have the same probability.

a(n) equals A047215(n) except for n=1.

			For n=1, there are four equally likely outcomes, 1,2,3,4, and the smallest of these is 1, so a(1)=1.

Colin Barker, Table of n, a(n) for n = 0..1000
Ran Pan, Exercise G, Project P
Index entries for linear recurrences with constant coefficients, signature (1,1,-1).

Cf. A030123, A047215.

[n le 1 select n else Floor(5*n/2): n in [0..70]]; // Vincenzo Librandi, Apr 08 2015

a:= n-> iquo(5*n, 2) -`if`(n=1, 1, 0):
seq(a(n), n=0..80);  # Alois P. Heinz, Apr 08 2015

Join[{0, 1}, Table[Floor[5 n/2], {n, 2, 100}]]

a(n)=if(n<2,n,5*n\2) \\ Charles R Greathouse IV, Apr 08 2015

concat(0, Vec(-x*(x^3-x^2-4*x-1)/((x-1)^2*(x+1)) + O(x^100))) \\ Colin Barker, Apr 08 2015

a(n) = floor(5*n/2), for n>=2; a(0)=0 and a(1)=1.
From Colin Barker, Apr 08 2015: (Start)
a(n) = (-1+(-1)^n+10*n)/4 for n>1.
a(n) = a(n-1)+a(n-2)-a(n-3) for n>4.
G.f.: -x*(x^3-x^2-4*x-1) / ((x-1)^2*(x+1)).
(End)
a(n)-a(n-1) = A010693(n-3), n>=3. - R. J. Mathar, Aug 08 2025

A032769 Numbers that are congruent to {0, 1, 2, 4} mod 5.

Original entry on oeis.org

0, 1, 2, 4, 5, 6, 7, 9, 10, 11, 12, 14, 15, 16, 17, 19, 20, 21, 22, 24, 25, 26, 27, 29, 30, 31, 32, 34, 35, 36, 37, 39, 40, 41, 42, 44, 45, 46, 47, 49, 50, 51, 52, 54, 55, 56, 57, 59, 60, 61, 62, 64, 65, 66, 67, 69, 70, 71, 72, 74, 75, 76, 77, 79, 80, 81, 82, 84, 85

Offset: 1

Patrick De Geest, May 15 1998

Also, numbers m such that m*(m+1)*(m+2)*(m+3)*(m+4)/(m+(m+1)+(m+2)+(m+3)+(m+4)) is an integer.

Index entries for linear recurrences with constant coefficients, signature (1,0,0,1,-1).

Cf. A001622, A032768, A032770, A047209, A047215.

[Floor((5*n - 4)/4) : n in [1..80]]; // Wesley Ivan Hurt, May 30 2016

seq(floor((5*n-4)/4), n=1..69); # Gary Detlefs, Mar 06 2010

Table[Floor[(5n - 4)/4], {n, 80}] (* Wesley Ivan Hurt, May 30 2016 *)

a(n)=5*n\4-1 \\ Charles R Greathouse IV, Jan 02 2025

a(n) = (1/8)*(10*n-11+(-1)^n+2*(-1)^floor(n/2)). - Ralf Stephan, Jun 09 2005
a(n) = floor((5*n-4)/4). - Gary Detlefs, Mar 06 2010
G.f.: x^2*(1+x+2*x^2+x^3) / ( (1+x)*(1+x^2)*(x-1)^2 ). - R. J. Mathar, Oct 08 2011
From Wesley Ivan Hurt, May 30 2016: (Start)
a(n) = a(n-1) + a(n-4) - a(n-5) for n>5.
a(n) = (10*n-11+i^(2*n)+(1+i)*I^(-n)+(1-i)*i^n)/8 where i=sqrt(-1).
a(2k) = A047209(k), a(2k-1) = A047215(k). (End)
E.g.f.: (4 + sin(x) + cos(x) + (5*x - 6)*sinh(x) + 5*(x - 1)*cosh(x))/4. - Ilya Gutkovskiy, May 31 2016
Sum_{n>=2} (-1)^n/a(n) = log(5)/4 + 3*sqrt(5)*log(phi)/10 - sqrt(1-2/sqrt(5))*Pi/10, where phi is the golden ratio (A001622). - Amiram Eldar, Dec 10 2021

Better description from Michael Somos, Jun 08 2000

A140869 Triangle read by rows where T(m,n) = floor((2mn+m+n-2)/2), m >= n >= 1.

Original entry on oeis.org

1, 2, 5, 4, 7, 11, 5, 10, 14, 19, 7, 12, 18, 23, 29, 8, 15, 21, 28, 34, 41, 10, 17, 25, 32, 40, 47, 55, 11, 20, 28, 37, 45, 54, 62, 71, 13, 22, 32, 41, 51, 60, 70, 79, 89, 14, 25, 35, 46, 56, 67, 77, 88, 98, 109, 16, 27, 39, 50, 62, 73, 85, 96, 108, 119, 131, 17, 30, 42, 55, 67, 80, 92, 105, 117, 130, 142, 155

Offset: 1

Vincenzo Librandi, Jan 16 2009

Conjecture: If h does not belong to the sequence, then 4*h+5 is prime. - Vincenzo Librandi, Nov 18 2012

First column: A001651; second column: A047215; third column: A047345. - Vincenzo Librandi, Nov 18 2012

			Triangle begins:
1;
2,  5;
4,  7,  11;
5,  10, 14, 19;
7,  12, 18, 23, 29;
8,  15, 21, 28, 34, 41;
10, 17, 25, 32, 40, 47, 55; etc.

Vincenzo Librandi, Rows n = 1..100, flattened

Cf. A002327, A153085, A001651, A047215, A047345.

[Floor(((2*n*k+n+k-2)/2)): k in [1..n], n in [1..11]]; // Vincenzo Librandi, Nov 18 2012

Flatten[Table[Floor[(2*n*m+m+n-2)/2],{n,1,10},{m,n}]] (* Vladimir Joseph Stephan Orlovsky, Feb 03 2012 *)

A038126 a(n) = floor( sqrt(2Pi)n ) (a Beatty sequence).

Original entry on oeis.org

0, 2, 5, 7, 10, 12, 15, 17, 20, 22, 25, 27, 30, 32, 35, 37, 40, 42, 45, 47, 50, 52, 55, 57, 60, 62, 65, 67, 70, 72, 75, 77, 80, 82, 85, 87, 90, 92, 95, 97, 100, 102, 105, 107, 110, 112, 115, 117, 120, 122, 125, 127, 130, 132, 135, 137, 140, 142, 145, 147, 150, 152, 155, 157

Offset: 0

N. J. A. Sloane, Felice Russo

nonn

Of course this is different from A047215 (they first differ at n=77).

G. C. Greubel, Table of n, a(n) for n = 0..10000
Eric Weisstein's World of Mathematics, Beatty Sequence.
Index entries for sequences related to Beatty sequences.

Cf. A019727, A047215.

R:= RealField(20); [Floor(n*Sqrt(2*Pi(R))): n in [0..100]]; // G. C. Greubel, Sep 08 2018

With[{c=Sqrt[2*Pi]},Floor[c*#]&/@Range[0,70]] (* Harvey P. Dale, Nov 14 2014 *)

vector(100, n, n--; floor(n*sqrt(2*Pi))) \\ G. C. Greubel, Sep 08 2018

cp's OEIS Frontend

A191740 Dispersion of A047220, (numbers >1 and congruent to 0 or 1 or 3 mod 5), by antidiagonals.

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A191741 Dispersion of A047217, (numbers >1 and congruent to 0 or 1 or 2 mod 5), by antidiagonals.

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A301568 Expansion of Product_{k>=1} (1 + x^(5*k))*(1 + x^(5*k-3)).

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A235089 a(n)*Pi is the total length of irregular spiral (center points: 2, 1, 3, 4) after n rotations.

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A183575 a(n) = n - 1 + ceiling((n^2-2)/2); complement of A183574.

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A256680 Minimal most likely sum for a roll of n 4-sided dice.

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A032769 Numbers that are congruent to {0, 1, 2, 4} mod 5.

A301568 Expansion of Product_{k>=1} (1 + x^(5k))(1 + x^(5*k-3)).

A038126 a(n) = floor( sqrt(2Pi)n ) (a Beatty sequence).