A286569 -id:A286569 - cp's OEIS frontend

A284019 The "Hofstadter chaotic heart" sequence: a(n) = A004001(n) - A005185(n).

0, 0, 0, -1, 0, 0, -1, -1, -1, 0, 1, -1, 0, 0, -2, -1, -1, -1, 0, 0, 0, 1, 2, -2, 1, 1, -1, 0, 0, 0, -4, -1, 0, -2, -2, 1, 1, -1, 1, 1, 1, 1, 1, 2, 2, 3, 3, -5, 4, 4, -1, 2, 4, 0, 1, 3, -1, 1, 0, 0, 0, 0, -8, -1, 2, -4, 0, 3, -2, -2, 1, 1, 0, 2, 2, 3, 1, 4, 4, 2, 2, 4, 4, 2, 4, 3, 2

Offset: 1

Altug Alkan, Mar 18 2017

See also scatterplot in Links section.
From Nathan Fox, Mar 30 2017: (Start)
The pattern in the graph presumably comes from the known pattern in the Conway sequence minus n/2 (A004001) combined with the "sausage" pattern of the Q-sequence (A005185). Since the Q-sequence seems to remain close to n/2, the patterns combine in this way.
This means that the bottoms of the hearts should be roughly at powers of 2 and the joins between them should be where the sausages thin out. (End) [Corrected by Altug Alkan, Apr 01 2017]
Note that this comment says that the indices where the bottoms of the hearts occur (the local minima) are roughly powers of 2. For example, a(8056) = -317 is a local minimum close to 2^13. - N. J. A. Sloane, Apr 01 2017

			a(4) = -1 since a(4) = A004001(4) - A005185(4) = 2 - 3 = -1.

Altug Alkan, Table of n, a(n) for n = 1..100000
Altug Alkan, Alternative Scatterplot of A284019
Altug Alkan, Nathan Fox, and Orhan Ozgur Aybar, On Hofstadter Heart Sequences, Complexity, 2017.
Index entries for Hofstadter-type sequences

Cf. A004001, A005185, A284606, A286560, A286569.

A005185:= proc(n) option remember; procname(n-procname(n-1)) +procname(n-procname(n-2)) end proc:
A005185(1):= 1: A005185(2):= 1:
A004001:= proc(n) option remember; procname(procname(n-1)) +procname(n-procname(n-1)) end proc:
A004001(1):= 1: A004001(2):= 1:
A284019:= map(A004001 - A005185, [$1..1000]):
seq(A284019[i], i=1..1000); # Altug Alkan, Mar 31 2017

a[n_] := a[n] = If[n <= 2, 1, a[a[n - 1]] + a[n - a[n - 1]]]; b[1] = b[2] = 1; b[n_] := b[n] = b[n - b[n - 1]] + b[n - b[n - 2]]; Table[a@ n - b@ n, {n, 87}] (* Michael De Vlieger, Mar 18 2017, after Robert G. Wilson v at A004001 *)

q=vector(1000); h=vector(1000); q[1]=q[2]=1; for(n=3, #q, q[n]=q[n-q[n-1]]+q[n-q[n-2]]); h[1]=h[2]=1; for(n=3, #h, h[n]=h[h[n-1]]+h[n-h[n-1]]); vector(1000, n, h[n]-q[n])

(define (A284019 n) (- (A004001 n) (A005185 n))) ;; Needs also Scheme-code included in those two entries. - Antti Karttunen, Mar 22 2017

Graphically descriptive name added by Antti Karttunen with permission from D. R. Hofstadter, Mar 29 2017

A286560 Compound filter (summands of A004001 & summands of A005185): a(n) = P(A286541(n), A286559(n)), where P(n,k) is sequence A000027 used as a pairing function, with a(1) = a(2) = 0.

Original entry on oeis.org

0, 0, 1, 2, 5, 41, 71, 71, 198, 313, 484, 922, 1153, 1201, 2105, 1565, 2588, 4046, 5001, 7443, 7443, 8851, 10671, 19589, 16570, 16935, 22254, 25313, 25313, 25313, 42891, 28793, 32768, 52795, 65504, 59178, 73355, 89033, 88632, 107660, 129045, 129045, 153471, 167646, 167646, 182446, 182446, 336130, 197244, 233297, 330472, 307358, 270167, 355325, 378466, 332156

Offset: 1

Antti Karttunen, May 18 2017

nonn

Antti Karttunen, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Pairing Function

Cf. A004001, A005185, A284019, A286541, A286559, A286569.

(define (A286560 n) (if (<= n 2) 0 (* (/ 1 2) (+ (expt (+ (A286541 n) (A286559 n)) 2) (- (A286541 n)) (- (* 3 (A286559 n))) 2))))

a(1) = a(2) = 0, for n > 2, a(n) = (1/2)*(2 + ((A286541(n)+A286559(n))^2) - A286541(n) - 3*A286559(n)).

A302780 Restricted growth sequence transform of 4-tuple [H(H(n-1)), H(n-H(n-1)), Q(n-Q(n-1)), Q(n-Q(n-2))] where H = A004001 and Q = A005185.

Original entry on oeis.org

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

Offset: 1

Antti Karttunen, Apr 27 2018

nonn

Restricted growth sequence transform of A286560: a filter sequence which includes both the summands of A004001 and the summands of A005185.
For all i, j: a(i) = a(j) => b(i) = b(j), where b is a sequence like A087740, A284019, A286569 or A302779.
For n > 1000 the duplicates get rare. In range [1000, 65536] there are only three cases: a(1353) = a(1354) = 1319, a(39361) = a(39362) = 39326, and a(46695) = a(46696) = 46659.

Antti Karttunen, Table of n, a(n) for n = 1..65537
Index entries for Hofstadter-type sequences

Cf. A004001, A005185, A286560.

Cf. also A087740, A284019, A286541, A286569, A302779.

up_to = 65537;
first_n_of_A004001(n) = { my(v=vector(n)); v[1]=v[2]=1; for(k=3, n, v[k]=v[v[k-1]]+v[k-v[k-1]]); (v); }; \\ Charles R Greathouse IV, Feb 26 2017
v004001 = first_n_of_A004001(up_to);
A004001(n) = v004001[n];
first_n_of_A005185(n) = { my(v=vector(n)); v[1]=v[2]=1; for(k=3, n, v[k]=v[k-v[k-1]]+v[k-v[k-2]]); (v); }; \\
v005185 = first_n_of_A005185(up_to);
A005185(n) = v005185[n];
Aux302780(n) = if(n<3,0,[A004001(A004001(n-1)), A004001(n-A004001(n-1)), A005185(n-A005185(n-1)), A005185(n-A005185(n-2))]);
rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };
write_to_bfile(start_offset,vec,bfilename) = { for(n=1, length(vec), write(bfilename, (n+start_offset)-1, " ", vec[n])); }
write_to_bfile(1,rgs_transform(vector(up_to,n,Aux302780(n))),"b302780.txt");

cp's OEIS Frontend

A284019 The "Hofstadter chaotic heart" sequence: a(n) = A004001(n) - A005185(n).

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A286560 Compound filter (summands of A004001 & summands of A005185): a(n) = P(A286541(n), A286559(n)), where P(n,k) is sequence A000027 used as a pairing function, with a(1) = a(2) = 0.

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A302780 Restricted growth sequence transform of 4-tuple [H(H(n-1)), H(n-H(n-1)), Q(n-Q(n-1)), Q(n-Q(n-2))] where H = A004001 and Q = A005185.

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