cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

A099965 First column (also row sums) of triangle in A099964.

Original entry on oeis.org

1, 1, 1, 2, 3, 8, 17, 39, 126, 352, 1026, 2943, 11429, 39138, 138903, 486490, 1711141, 7720713, 31383260, 131236182, 543056039, 2254646235, 9349845765, 48137959377, 226341090088, 1090094720010, 5203693239201, 24909594299924
Offset: 0

Views

Author

N. J. A. Sloane, Nov 13 2004

Keywords

Crossrefs

Cf. A099964.

Programs

  • Haskell
    a099965 = flip a099964 0
    a099965_list = map head a099964_tabf
    -- Reinhard Zumkeller, May 02 2012
  • Maple
    with(linalg):rev:=proc(a) local n, p; n:=vectdim(a): p:=i->a[n+1-i]: vector(n,p) end: ps:=proc(a) local n, q; n:=vectdim(a): q:=i->sum(a[j],j=1..i): vector(n,q) end: pss:=proc(a) local n, q; n:=vectdim(a): q:=proc(i) if i<=n then sum(a[j],j=1..i) else sum(a[j],j=1..n) fi end: vector(n+1,q) end: tr:={seq(n*(n+1)/2,n=1..30)}: R[0]:=vector(1,1): for n from 1 to 31 do if member(n,tr)=false then R[n]:=ps(rev(R[n-1])) else R[n]:=pss(rev(R[n-1])) fi od: seq(R[n][1],n=0..31); # Emeric Deutsch, Nov 16 2004
  • Mathematica
    triQ[n_] := Reduce[n == k (k + 1)/2, k, Integers] =!= False; row[0] = {1}; row[1] = {1, 1}; row[n_] := row[n] = (ro = Accumulate[Reverse[row[n-1]]]; If[triQ[n], Append[ro, Last[ro]], ro]); Table[row[n][[1]], {n, 0, 27}] (* Jean-François Alcover, Feb 10 2018 *)

Extensions

More terms from Emeric Deutsch, Nov 16 2004

A099966 Sequence of the next-to-last entries in the rows of A099964.

Original entry on oeis.org

1, 1, 3, 6, 14, 39, 109, 313, 900, 2943, 10403, 36195, 127474, 447352, 1711141, 7234223, 29672119, 123515469, 511672779, 2123410053, 9349845765, 45883313142, 216991244323, 1041956760633, 4977352149113, 23819499579914
Offset: 1

Views

Author

N. J. A. Sloane, Nov 13 2004

Keywords

Crossrefs

Programs

  • Haskell
    a099966 n = a099966_list !! (n-1)
    a099966_list = map (last . init) $ tail a099964_tabf
    -- Reinhard Zumkeller, May 02 2012
  • Maple
    with(linalg):rev:=proc(a) local n, p; n:=vectdim(a): p:=i->a[n+1-i]: vector(n,p) end: ps:=proc(a) local n, q; n:=vectdim(a): q:=i->sum(a[j],j=1..i): vector(n,q) end: pss:=proc(a) local n, q; n:=vectdim(a): q:=proc(i) if i<=n then sum(a[j],j=1..i) else sum(a[j],j=1..n) fi end: vector(n+1,q) end: tr:={seq(n*(n+1)/2,n=1..30)}: R[0]:=vector(1,1): for n from 1 to 30 do if member(n,tr)=false then R[n]:=ps(rev(R[n-1])) else R[n]:=pss(rev(R[n-1])) fi od: seq(R[n][vectdim(R[n])-1],n=1..30); # Emeric Deutsch, Nov 16 2004
  • Mathematica
    triQ[n_] := Module[{k}, Reduce[n == k (k + 1)/2, k, Integers] =!= False];
    row[0] = {1}; row[1] = {1, 1}; row[n_] := row[n] = (ro = Accumulate[ Reverse[ row[n - 1]]]; If[triQ[n], Append[ro, Last[ro]], ro]); a[n_] := row[n][[-2]]; Array[a, 26] (* Jean-François Alcover, Feb 13 2018 *)

Extensions

More terms from Emeric Deutsch, Nov 16 2004
Offset corrected by Reinhard Zumkeller, May 02 2012

A099968 Second column of triangle in A099964.

Original entry on oeis.org

1, 2, 3, 6, 14, 31, 78, 235, 665, 1926, 5886, 21832, 75333, 266377, 933842, 3422282, 14954936, 61055379, 254751651, 1054728818, 4378056288, 18699691530, 94021272519, 443332334411, 2132051480643, 10181045388314, 48729093879838
Offset: 1

Views

Author

N. J. A. Sloane, Nov 13 2004

Keywords

Crossrefs

Programs

  • Haskell
    a099968 = flip a099964 1 -- Reinhard Zumkeller, May 02 2012
  • Maple
    with(linalg):rev:=proc(a) local n, p; n:=vectdim(a): p:=i->a[n+1-i]: vector(n,p) end: ps:=proc(a) local n, q; n:=vectdim(a): q:=i->sum(a[j],j=1..i): vector(n,q) end: pss:=proc(a) local n, q; n:=vectdim(a): q:=proc(i) if i<=n then sum(a[j],j=1..i) else sum(a[j],j=1..n) fi end: vector(n+1,q) end: tr:={seq(n*(n+1)/2,n=1..30)}: R[0]:=vector(1,1): for n from 1 to 30 do if member(n,tr)=false then R[n]:=ps(rev(R[n-1])) else R[n]:=pss(rev(R[n-1])) fi od: seq(R[n][2],n=1..30); # Emeric Deutsch, Nov 16 2004

Extensions

More terms from Emeric Deutsch, Nov 16 2004
Offset corrected by Reinhard Zumkeller, May 02 2012
Showing 1-3 of 3 results.