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.

A379005 Lexicographically earliest infinite sequence such that a(i) = a(j) => v_2(i) = v_2(j), v_3(i) = v_3(j) and v_5(i) = v_5(j), for all i, j, where v_2 (A007814), v_3 (A007949) and v_5 (A112765) give the 2-, 3- and 5-adic valuations of n respectively.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Dec 15 2024

Keywords

Comments

Restricted growth sequence transform of A355582.
For all i, j:
A379001(i) = A379001(j) => a(i) = a(j),
a(i) = a(j) => A322026(i) = A322026(j),
a(i) = a(j) => A379004(i) = A379004(j).

Crossrefs

Cf. A007814, A007949, A112765, A355582, A379006 (ordinal transform).

Programs

  • PARI
    up_to = 100000;
    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; };
    v379005 = rgs_transform(vector(up_to, n, [valuation(n,2), valuation(n,3), valuation(n,5)]));
    A379005(n) = v379005[n];

A379002 Lexicographically earliest infinite sequence such that a(i) = a(j) => A046523(i) = A046523(j) and A112765(i) = A112765(j), for all i, j, where A046523 gives the least representative of the prime signature of n and A112765 gives the 5-adic valuation of n.

Original entry on oeis.org

1, 2, 2, 3, 4, 5, 2, 6, 3, 7, 2, 8, 2, 5, 7, 9, 2, 8, 2, 10, 5, 5, 2, 11, 12, 5, 6, 8, 2, 13, 2, 14, 5, 5, 7, 15, 2, 5, 5, 16, 2, 17, 2, 8, 10, 5, 2, 18, 3, 19, 5, 8, 2, 11, 7, 11, 5, 5, 2, 20, 2, 5, 8, 21, 7, 17, 2, 8, 5, 13, 2, 22, 2, 5, 19, 8, 5, 17, 2, 23, 9, 5, 2, 24, 7, 5, 5, 11, 2, 20, 5, 8, 5, 5, 7, 25, 2, 8, 8, 26, 2, 17, 2, 11, 13
Offset: 1

Views

Author

Antti Karttunen, Dec 15 2024

Keywords

Comments

Restricted growth sequence transform of ordered pair [A046523(n), A112765(n)].
For all i, j:
A379001(i) = A379001(j) => a(i) = a(j).

Crossrefs

Programs

  • PARI
    up_to = 100000;
    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; };
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); };
    v379002 = rgs_transform(vector(up_to, n, [A046523(n), valuation(n,5)]));
    A379002(n) = v379002[n];

A379000 Lexicographically earliest infinite sequence such that a(i) = a(j) => f(i) = f(j), where f(n) = 0 if n is prime > 5, with f(n) = n for all other n.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Dec 15 2024

Keywords

Comments

For all i, j:
a(i) = a(j) => A305900(i) = A305900(j) => A305801(i) = A305801(j) => A305800(i) = A305800(j),
a(i) = a(j) => A379001(i) = A379001(j) => A379002(i) = A379002(j),
a(i) = a(j) => A379005(i) = A379005(j).

Crossrefs

Programs

  • PARI
    A379000(n) = if(n<=7, n, if(isprime(n), 7, 4+n-primepi(n)));

Formula

For n < 7, a(n) = n, for primes > 5, a(n) = 7, and for composite n > 7, a(n) = 4+n-A000720(n).
Showing 1-3 of 3 results.