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.

A351963 Lexicographically earliest infinite sequence such that a(i) = a(j) => A278222(A109812(i)) = A278222(A109812(j)), for all i, j >= 1.

Original entry on oeis.org

1, 1, 1, 2, 1, 3, 3, 1, 2, 3, 3, 2, 3, 4, 1, 4, 2, 3, 3, 5, 3, 5, 3, 6, 3, 5, 2, 7, 1, 5, 6, 3, 5, 5, 3, 5, 6, 3, 8, 2, 9, 3, 5, 4, 5, 5, 3, 8, 5, 1, 8, 5, 3, 7, 5, 3, 10, 6, 3, 6, 6, 5, 6, 5, 6, 5, 5, 4, 8, 3, 9, 5, 5, 7, 2, 11, 3, 10, 3, 10, 6, 6, 9, 5, 8, 6, 5, 8, 5, 10, 6, 12, 6, 10, 6, 5, 10, 4, 6, 8, 5, 13
Offset: 1

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Author

Antti Karttunen, Apr 06 2022

Keywords

Comments

Restricted growth sequence transform of A278222(A109812(n)), or equally of, A278222(A351965(n)).
For all i, j: A351578(i) = A351578(j) => a(i) = a(j) => A352884(i) = A352884(j).

Crossrefs

Programs

  • PARI
    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; };
    v109812 = readvec("b109812_to10e5.txt"); \\ Prepared from b-file data with gawk ' { print $2 } '
    up_to = #v109812;
    A109812(n) = v109812[n];
    A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); (t); };
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); }; \\ From A046523
    v351963 = rgs_transform(vector(up_to, n, A046523(A005940(1+A109812(n)))));
    A351963(n) = v351963[n];

A351964 The 2-adic valuation of A109812(n); The exponent of the highest power of 2 dividing A109812(n).

Original entry on oeis.org

0, 1, 2, 0, 3, 0, 1, 4, 1, 0, 1, 2, 0, 1, 5, 0, 3, 0, 2, 0, 2, 0, 3, 0, 1, 0, 4, 0, 6, 1, 0, 1, 0, 1, 0, 1, 0, 3, 0, 5, 0, 2, 0, 2, 0, 2, 4, 0, 3, 7, 0, 1, 0, 1, 0, 1, 0, 1, 2, 1, 0, 1, 0, 2, 1, 0, 1, 3, 0, 3, 0, 2, 0, 2, 6, 0, 5, 0, 4, 0, 2, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 2, 0, 4, 0, 1, 2, 0, 8, 0, 4
Offset: 1

Views

Author

Antti Karttunen, Apr 07 2022

Keywords

Crossrefs

Programs

  • PARI
    v109812 = readvec("b109812_to10e5.txt"); \\ Prepared from b-file data with gawk ' { print $2 } '
    up_to = #v109812;
    A109812(n) = v109812[n];
    A007814(n) = valuation(n,2);
    A351964(n) = A007814(A109812(n));
    
  • Python
    from itertools import count, islice
    def A351964_gen(): # generator of terms
        yield 0
        l1, s, b = 1, 2, set()
        while True:
            for i in count(s):
                if not (i in b or i & l1):
                    yield (~i&i-1).bit_length()
                    l1 = i
                    b.add(i)
                    while s in b:
                        b.remove(s)
                        s += 1
                    break
    A351964_list = list(islice(A351964_gen(),30)) # Chai Wah Wu, Jul 16 2022

Formula

a(n) = A007814(A109812(n)).

A352888 Lexicographically earliest infinite sequence such that a(i) = a(j) => A278219(A109812(i)) = A278219(A109812(j)), for all i, j >= 1.

Original entry on oeis.org

1, 2, 2, 1, 2, 3, 4, 2, 5, 6, 7, 5, 6, 5, 2, 1, 5, 6, 4, 3, 7, 6, 4, 8, 7, 6, 5, 1, 2, 9, 10, 7, 11, 12, 6, 9, 13, 7, 3, 5, 6, 7, 6, 5, 6, 9, 4, 6, 9, 2, 6, 12, 6, 5, 11, 7, 13, 14, 7, 15, 13, 12, 16, 9, 14, 11, 12, 5, 6, 7, 11, 12, 6, 5, 5, 1, 4, 13, 7, 8, 15, 16, 12, 11, 9, 10, 12, 11, 12, 10, 14, 17, 14, 16, 18
Offset: 1

Views

Author

Antti Karttunen, Apr 07 2022

Keywords

Comments

Restricted growth sequence transform of A278219(A109812(n)).
For all i, j: a(i) = a(j) => A352889(i) = A352889(j).

Crossrefs

Programs

  • PARI
    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; };
    v109812 = readvec("b109812_to10e5.txt"); \\ Prepared from b-file data with gawk ' { print $2 } '
    up_to = #v109812;
    A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); t };
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); };  \\ From A046523
    A003188(n) = bitxor(n, n>>1);
    A278219(n) = A046523(A005940(1+A003188(n)));
    A109812(n) = v109812[n];
    v352888 = rgs_transform(vector(up_to, n, A278219(A109812(n))));
    A352888(n) = v352888[n];
Showing 1-3 of 3 results.