A351090 - OEIS

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A351090

Lexicographically earliest infinite sequence such that a(i) = a(j) => A351091(i) = A351091(j) and A351092(i) = A351092(j), for all i, j >= 1.

1, 1, 2, 1, 3, 2, 4, 1, 5, 3, 6, 2, 7, 4, 8, 1, 9, 5, 10, 3, 11, 6, 12, 2, 13, 7, 14, 4, 15, 8, 16, 1, 17, 9, 18, 5, 19, 10, 20, 3, 21, 11, 22, 6, 23, 12, 24, 2, 25, 13, 26, 7, 27, 14, 28, 4, 29, 15, 30, 8, 31, 16, 32, 1, 33, 17, 34, 9, 35, 18, 36, 5, 37, 19, 38, 10, 39, 20, 40, 3, 41, 21, 42, 11, 43, 22, 44, 6, 45, 23

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OFFSET

1,3

COMMENTS

Restricted growth sequence transform of the ordered pair [A351091(n), A351092(n)], or equally, of the ordered pair [A351093(n), A351094(n)].

For all i, j: A003602(i) = A003602(j) => a(i) = a(j) => A000593(i) = A000593(j).

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..65537

EXAMPLE

Consider two odd semiprimes, 689 and 697. The divisors of 689 are 1, 13, 53, 689, and the divisors of 697 are 1, 17, 41, 697. Applying A019565(A289813(x)) to the former gives [2, 30, 7, 105], while with the latter it gives [2, 5, 105, 42], and the product of both sequences is 44100. Applying A019565(A289814(x)) to the former gives [1, 1, 30, 286], while with the latter it gives [1, 6, 2, 715]. Product of both sequences is 8580. Therefore, because A351091(689) = A351091(697) and A351092(689) = A351092(697), also a(689) = a(697).

PROG

(PARI)

up_to = 65537;

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; };

A019565(n) = { my(m=1, p=1); while(n>0, p = nextprime(1+p); if(n%2, m *= p); n >>= 1); (m); };

A289813(n) = { my(d=digits(n, 3)); fromdigits(vector(#d, i, if (d[i]==1, 1, 0)), 2); }; \\ From A289813

A289814(n) = { my (d=digits(n, 3)); fromdigits(vector(#d, i, if (d[i]==2, 1, 0)), 2); }; \\ From A289814

A351091(n) = { my(m=1); fordiv(n>>valuation(n, 2), d, m *= A019565(A289813(d))); (m); };

A351092(n) = { my(m=1); fordiv(n>>valuation(n, 2), d, m *= A019565(A289814(d))); (m); };

Aux351090(n) = [A351091(n), A351092(n)];

v351090 = rgs_transform(vector(up_to, n, Aux351090(n)));

A351090(n) = v351090[n];

CROSSREFS

Cf. A000593, A351037, A351091, A351092, A351093, A351094.

Differs from A003602 for the first time at n=697, where a(697) = 345 while A003602(697) = 349.

Cf. also A293226, A351030.

Sequence in context: A366881 A366891 A003602 * A366893 A365388 A366380

Adjacent sequences: A351087 A351088 A351089 * A351091 A351092 A351093

KEYWORD

nonn,easy

AUTHOR

Antti Karttunen, Jan 31 2022

STATUS

approved