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 1-8 of 8 results.

A277023 a(n) = A276573(A260732(n)); For n >= 1, a(n) = the next larger term right after each (n^2)-1 in the infinite trunk of least squares beanstalk.

Original entry on oeis.org

0, 3, 6, 11, 16, 27, 38, 51, 64, 83, 102, 123, 144, 171, 198, 227, 256, 291, 326, 361, 400, 444, 486, 531, 576, 627, 678, 731, 786, 843, 902, 963, 1026, 1091, 1158, 1227, 1296, 1371, 1446, 1523, 1600, 1683, 1767, 1851, 1938, 2025, 2118, 2211, 2304, 2403, 2502, 2603, 2706, 2811, 2918, 3027, 3136, 3251, 3366, 3483, 3600, 3723, 3846
Offset: 0

Views

Author

Antti Karttunen, Oct 03 2016

Keywords

Crossrefs

Cf. A277015 (the positions of squares in this sequence), A277024, A277025 A277026.

Programs

Formula

a(n) = A276573(A260732(n)).

A276572 Simple self-inverse permutation of natural numbers: after a(0)=0, list each block of A260734(n) numbers in reverse order, from A260732(n) to A260733(1+n).

Original entry on oeis.org

0, 1, 3, 2, 5, 4, 9, 8, 7, 6, 13, 12, 11, 10, 18, 17, 16, 15, 14, 23, 22, 21, 20, 19, 30, 29, 28, 27, 26, 25, 24, 37, 36, 35, 34, 33, 32, 31, 44, 43, 42, 41, 40, 39, 38, 52, 51, 50, 49, 48, 47, 46, 45, 62, 61, 60, 59, 58, 57, 56, 55, 54, 53, 71, 70, 69, 68, 67, 66, 65, 64, 63, 81, 80, 79, 78, 77, 76, 75, 74, 73, 72
Offset: 0

Views

Author

Antti Karttunen, Sep 07 2016

Keywords

Comments

Maps between A276573 and A276574.

Crossrefs

Programs

  • Mathematica
    f[n_] := NestWhileList[# - (If[First@ # > 0, 1, Length[First@ Split@ #] + 1] &@ SquaresR[Range@ 4, #]) &, n^2, # != 0 &]; t = Table[Table[n, {Length[#] - 1 &@ NestWhileList[# - (If[First@ # > 0, 1, Length[First@ Split@ #] + 1] &@ SquaresR[Range@ 4, #]) &, ((n + 1)^2) - 1, # != (n^2) - 1 &]}], {n, 20}] // Flatten ; {0}~Join~Table[Length@ f@ t[[n]] - 1 + Length@ f[t[[n]] + 1] - n - 2, {n, 81}] (* Michael De Vlieger, Sep 08 2016 *)
  • Scheme
    (define (A276572 n) (if (zero? n) n (+ (- (A260733 (+ 1 (A276571 n))) n) (A260732 (A276571 n)))))

Formula

a(0) = 0; for n >= 1, a(n) = (A260733(1+A276571(n))-n)+A260732(A276571(n)).

A255131 n minus the least number of squares that add up to n: a(n) = n - A002828(n).

Original entry on oeis.org

0, 0, 0, 0, 3, 3, 3, 3, 6, 8, 8, 8, 9, 11, 11, 11, 15, 15, 16, 16, 18, 18, 19, 19, 21, 24, 24, 24, 24, 27, 27, 27, 30, 30, 32, 32, 35, 35, 35, 35, 38, 39, 39, 40, 41, 43, 43, 43, 45, 48, 48, 48, 50, 51, 51, 51, 53, 54, 56, 56, 56, 59, 59, 59, 63, 63, 63, 64, 66, 66, 67, 67, 70, 71, 72, 72, 73, 74, 75, 75, 78, 80, 80, 80, 81
Offset: 0

Views

Author

Antti Karttunen, Feb 24 2015

Keywords

Comments

The associated beanstalk-sequence starts from a(0) as: 0, 3, 6, 8, 11, 15, 16, 18, 21, ... (A276573).

Examples

			a(0) = 0, because no squares are needed for an empty sum, and 0 - 0 = 0.
a(3) = 0, because 3 cannot be represented as a sum of less than three squares (1+1+1), and 3 - 3 = 0.
a(4) = 3, because 4 can be represented as a sum of just one square (namely 4 itself), and 4 - 1 = 3.
		

Crossrefs

Programs

  • Maple
    f:= proc(n) local F, x;
       if issqr(n) then return n-1 fi;
       if nops(select(t -> t[1] mod 4 = 3 and t[2]::odd, ifactors(n)[2])) = 0 then return n-2 fi;
       x:= n/4^floor(padic:-ordp(n, 2)/2);
       if x mod 8 = 7 then n-4 else n-3 fi
    end proc:
    f(0):= 0:
    map(f, [$0..100]); # Robert Israel, Mar 27 2018
  • Mathematica
    {0}~Join~Table[n - (If[First@ # > 0, 1, Length[First@ Split@ #] + 1] &@ SquaresR[Range@ 4, n]), {n, 84}] (* Michael De Vlieger, Sep 08 2016, after Harvey P. Dale at A002828 *)

Formula

a(n) = n - A002828(n).
a(n) = A260740(n) + A062535(n).

A260731 a(n) = Number of steps to reach 0 starting from x=n and using the iterated process: x -> x - A002828(x), where A002828(x) = the least number of squares that add up to x.

Original entry on oeis.org

0, 1, 1, 1, 2, 2, 2, 2, 3, 4, 4, 4, 5, 5, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 9, 10, 10, 10, 10, 11, 11, 11, 12, 12, 13, 13, 14, 14, 14, 14, 15, 15, 15, 16, 16, 17, 17, 17, 18, 19, 19, 19, 20, 20, 20, 20, 21, 21, 22, 22, 22, 23, 23, 23, 24, 24, 24, 25, 25, 25, 26, 26, 27, 27, 28, 28, 28, 29, 29, 29, 30, 31, 31, 31, 32, 32, 32, 32, 33, 33, 34, 34, 34, 35, 35, 35, 36, 36, 37, 37, 38
Offset: 0

Views

Author

Antti Karttunen, Aug 12 2015

Keywords

Crossrefs

Left inverse of A276573, A278517 and A278519. A278518(n) gives the number of times n occurs (run lengths).
Cf. also A261221.

Programs

  • Mathematica
    A002828[n_] := Which[n == 0, 0, SquaresR[1, n] > 0, 1, SquaresR[2, n] > 0, 2, SquaresR[3, n] > 0, 3, True, 4]; a[0] = 0; a[n_] := a[n] = 1 + a[n - A002828[n]]; Table[a[n], {n, 0, 100}] (* Jean-François Alcover, Nov 14 2016 *)

Formula

a(0) = 0; for >= 1, a(n) = 1 + A260731(A255131(n)).
From Antti Karttunen, Nov 28 2016: (Start)
For all n >= 0, a(A278517(n)) = a(A278519(n)) = a(A276573(n)) = n.
(End)

A260733 a(n) = number of steps needed to reach zero when starting from k = (n^2)-1 and repeatedly applying the map that replaces k with k - A002828(k), where A002828(k) = the least number of squares that add up to k.

Original entry on oeis.org

0, 1, 3, 5, 9, 13, 18, 23, 30, 37, 44, 52, 62, 71, 81, 91, 104, 117, 131, 144, 159, 174, 190, 207, 224, 243, 262, 281, 301, 321, 343, 365, 388, 412, 437, 461, 487, 514, 539, 567, 596, 625, 654, 684, 715, 748, 781, 814, 848, 883, 918, 955, 991, 1030, 1067, 1105, 1145, 1187, 1227, 1269, 1311, 1354, 1396, 1441, 1486, 1531, 1579, 1624, 1673, 1723, 1773, 1821
Offset: 1

Views

Author

Antti Karttunen, Aug 12 2015

Keywords

Crossrefs

One less than A260732.
Cf. also A261223.

Programs

  • Mathematica
    Table[Length[#] - 2 &@ NestWhileList[# - (If[First@ # > 0, 1, Length[ First@ Split@ #] + 1] &@ SquaresR[Range@ 4, #]) &, n^2, # != 0 &], {n, 72}] (* Michael De Vlieger, Sep 08 2016 *)

Formula

a(n) = A260731((n^2)-1).
a(n) = A260732(n)-1.

A260734 a(n) = number of steps needed to reach (n^2)-1 when starting from k = ((n+1)^2)-1 and repeatedly applying the map that replaces k with k - A002828(k), where A002828(k) = the least number of squares that add up to k.

Original entry on oeis.org

1, 2, 2, 4, 4, 5, 5, 7, 7, 7, 8, 10, 9, 10, 10, 13, 13, 14, 13, 15, 15, 16, 17, 17, 19, 19, 19, 20, 20, 22, 22, 23, 24, 25, 24, 26, 27, 25, 28, 29, 29, 29, 30, 31, 33, 33, 33, 34, 35, 35, 37, 36, 39, 37, 38, 40, 42, 40, 42, 42, 43, 42, 45, 45, 45, 48, 45, 49, 50, 50, 48, 53, 50, 51, 54, 52, 53, 54, 56, 56, 56, 58, 59, 59, 60, 60, 60, 61, 62, 62, 62, 65, 66, 66, 65
Offset: 1

Views

Author

Antti Karttunen, Aug 12 2015

Keywords

Crossrefs

First differences of both A260732 and A260733.
Cf. also A261224.

Programs

  • Mathematica
    Table[Length[#] - 1 &@ NestWhileList[# - (If[First@ # > 0, 1, Length[ First@ Split@ #] + 1] &@ SquaresR[Range@ 4, #]) &, ((n + 1)^2) - 1, # != (n^2) - 1 &], {n, 95}] (* Michael De Vlieger, Sep 08 2016, after Harvey P. Dale at A002828 *)

Formula

a(n) = A260731(((n+1)^2)-1) - A260731((n^2)-1). [The definition.]
Equally, for all n >= 1:
a(n) = A260731((n+1)^2) - A260731(n^2).
a(n) = A260732(n+1) - A260732(n).
a(n) = A260733(n+1) - A260733(n).

A261088 Number of steps needed to reach zero when starting from k = n^2 and repeatedly applying the map that replaces k with k - d(k), where d(k) is the number of divisors of k (A000005).

Original entry on oeis.org

0, 1, 2, 3, 5, 6, 10, 10, 19, 15, 19, 21, 24, 28, 39, 33, 53, 44, 49, 53, 60, 61, 69, 72, 79, 82, 92, 93, 117, 108, 115, 115, 140, 121, 174, 146, 205, 155, 233, 217, 267, 192, 295, 209, 225, 222, 238, 249, 267, 270, 299, 290, 336, 313, 373, 328, 411, 347, 451, 380, 486, 400, 534, 422, 447, 441, 460, 460, 511, 479, 496, 504, 545, 529, 602, 553, 579, 577, 626, 612, 681, 632, 747, 665, 796, 695
Offset: 0

Views

Author

Antti Karttunen, Sep 23 2015

Keywords

Crossrefs

Programs

  • Mathematica
    f[n_]:=Length[NestWhileList[#-DivisorSigma[0,#]&,n^2,#!= 0&]]-1;f/@Range[0,85] (* Ivan N. Ianakiev, Sep 25 2015 *)
  • PARI
    allocatemem((2^31)+(2^30));
    uplim = 2^25;
    v155043 = vector(uplim);
    v155043[1] = 1; v155043[2] = 1;
    for(i=3, uplim, v155043[i] = 1 + v155043[i-numdiv(i)]; if(!(i%65536),print1(i,", ")););
    A155043 = n -> if(!n,n,v155043[n]);
    A261088 = n -> A155043(n^2);
    for(n=0, 5792, write("b261088.txt", n, " ", A261088(n)));
    
  • Scheme
    (define (A261088 n) (A155043 (A000290 n)))

Formula

a(n) = A155043(A000290(n)) = A155043(n^2).

A261222 a(n) = number of steps to reach 0 when starting from k = n*n and repeatedly applying the map that replaces k with k - A053610(k), where A053610(k) = the number of positive squares that sum to k using the greedy algorithm.

Original entry on oeis.org

0, 1, 2, 4, 6, 9, 12, 15, 19, 24, 29, 35, 41, 48, 55, 62, 70, 78, 87, 97, 107, 118, 129, 141, 153, 165, 178, 191, 205, 219, 234, 249, 265, 282, 299, 317, 335, 354, 373, 392, 412, 433, 454, 475, 497, 519, 542, 565, 589, 613, 638, 664, 690, 717, 744, 772, 800, 828, 857, 887, 917, 948, 979, 1010, 1042, 1074, 1107, 1140, 1174, 1208, 1243, 1278, 1314, 1351, 1388, 1426, 1464, 1503
Offset: 0

Views

Author

Antti Karttunen, Aug 12 2015

Keywords

Crossrefs

Essentially one more than A261223.
First differences: A261224.
Cf. also A260732, A261227.

Programs

  • Mathematica
    Table[-1 + Length@ NestWhileList[# - Block[{m = #, c = 1}, While[a = (# - Floor[Sqrt@ #]^2) &@ m; a != 0, c++; m = a]; c] &, n^2, # != 0 &], {n, 0, 77}] (* Michael De Vlieger, Sep 08 2016, after Jud McCranie at A053610 *)

Formula

a(n) = A261221(n^2).
Other identities. For all n >= 1:
a(n) = 1 + A261223(n).
Showing 1-8 of 8 results.