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 1-5 of 5 results.

A348949 a(n) = A003959(A276086(n)), where A003959 is multiplicative with a(p^e) = (p+1)^e, and A276086 gives the prime product form of primorial base expansion of n.

Original entry on oeis.org

1, 3, 4, 12, 16, 48, 6, 18, 24, 72, 96, 288, 36, 108, 144, 432, 576, 1728, 216, 648, 864, 2592, 3456, 10368, 1296, 3888, 5184, 15552, 20736, 62208, 8, 24, 32, 96, 128, 384, 48, 144, 192, 576, 768, 2304, 288, 864, 1152, 3456, 4608, 13824, 1728, 5184, 6912, 20736, 27648, 82944, 10368, 31104, 41472, 124416, 165888, 497664, 64
Offset: 0

Views

Author

Antti Karttunen, Nov 07 2021

Keywords

Crossrefs

Programs

  • PARI
    A348949(n) = { my(m=1, p=2); while(n, m *= ((1+p)^(n%p)); n = n\p; p = nextprime(1+p)); (m); };

Formula

a(n) = A003959(A276086(n)).
a(n) = A276086(n) + A348950(n).

A348929 a(n) = gcd(n, A003959(n)), where A003959 is multiplicative with a(p^e) = (p+1)^e.

Original entry on oeis.org

1, 1, 1, 1, 1, 6, 1, 1, 1, 2, 1, 12, 1, 2, 3, 1, 1, 6, 1, 2, 1, 2, 1, 12, 1, 2, 1, 4, 1, 6, 1, 1, 3, 2, 1, 36, 1, 2, 1, 2, 1, 6, 1, 4, 3, 2, 1, 12, 1, 2, 3, 2, 1, 6, 1, 8, 1, 2, 1, 12, 1, 2, 1, 1, 1, 6, 1, 2, 3, 2, 1, 72, 1, 2, 3, 4, 1, 6, 1, 2, 1, 2, 1, 12, 1, 2, 3, 4, 1, 18, 7, 4, 1, 2, 5, 12, 1, 2, 3, 4, 1, 6, 1, 2, 3
Offset: 1

Views

Author

Antti Karttunen, Nov 07 2021

Keywords

Crossrefs

Differs from similar A126795 for the first time at n=36, where a(36) = 36, while A126795(36) = 12.

Programs

  • Mathematica
    f[p_, e_] := (p + 1)^e; a[n_] := GCD[n, Times @@ f @@@ FactorInteger[n]]; Array[a, 100] (* Amiram Eldar, Nov 07 2021 *)
  • PARI
    A003959(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1]++); factorback(f); };
    A348929(n) = gcd(n, A003959(n));

Formula

a(n) = gcd(n, A003959(n)) = gcd(n, A348507(n)) = gcd(A003959(n), A348507(n)).

A348950 a(n) = A348507(A276086(n)), where A348507(n) = A003959(n) - n, A003959 is multiplicative with a(p^e) = (p+1)^e, and A276086 gives the prime product form of primorial base expansion of n.

Original entry on oeis.org

0, 1, 1, 6, 7, 30, 1, 8, 9, 42, 51, 198, 11, 58, 69, 282, 351, 1278, 91, 398, 489, 1842, 2331, 8118, 671, 2638, 3309, 11802, 15111, 50958, 1, 10, 11, 54, 65, 258, 13, 74, 87, 366, 453, 1674, 113, 514, 627, 2406, 3033, 10674, 853, 3434, 4287, 15486, 19773, 67194, 5993, 22354, 28347, 98166, 126513, 418914, 15, 94, 109
Offset: 0

Views

Author

Antti Karttunen, Nov 06 2021

Keywords

Crossrefs

Programs

  • PARI
    A003959(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1]++); factorback(f); };
    A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
    A348507(n) = (A003959(n) - n);
    A348950(n) = A348507(A276086(n));
    
  • PARI
    A348950(n) = { my(m1=1, m2=1, p=2); while(n, m1 *= (p^(n%p)); m2 *= ((1+p)^(n%p)); n = n\p; p = nextprime(1+p)); (m2-m1); };

Formula

a(n) = A348949(n) - A276086(n) = A348507(A276086(n)).

A348998 a(n) = A348928(A276086(n)), where A348928(n) = gcd(n, A003958(n)), and A003958 is multiplicative with a(p^e) = (p-1)^e, and A276086 gives the prime product form of primorial base expansion of n.

Original entry on oeis.org

1, 1, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 3, 6, 3, 6, 1, 2, 3, 6, 3, 6, 1, 2, 3, 6, 3, 6, 1, 2, 3, 6, 3, 6, 1, 2, 3, 6, 3, 6, 1, 2, 3, 6, 9, 18, 1, 2, 3, 6, 9, 18, 1, 2, 3, 6, 9, 18, 1, 2, 3, 6, 9, 18, 1, 2, 3, 6, 9, 18, 1, 2, 3, 6, 9, 18, 1, 2, 3, 6, 9, 18
Offset: 0

Views

Author

Antti Karttunen, Nov 07 2021

Keywords

Comments

After each primorial number (A002110), the apparent periodicity grows more complex.

Crossrefs

Programs

  • PARI
    A348998(n) = { my(m1=1, m2=1, p=2); while(n, m1 *= (p^(n%p)); m2 *= ((p-1)^(n%p)); n = n\p; p = nextprime(1+p)); gcd(m1,m2); };

A349000 a(n) = A323166(A276086(n)), where A323166(n) = gcd(n, usigma(n)), usigma (A034448) is multiplicative with a(p^e) = (p^e)+1, and A276086 gives the prime product form of primorial base expansion of n.

Original entry on oeis.org

1, 1, 1, 6, 1, 6, 1, 2, 3, 6, 15, 90, 1, 2, 1, 6, 5, 30, 1, 2, 3, 6, 45, 90, 1, 2, 1, 6, 5, 30, 1, 2, 1, 6, 1, 6, 1, 2, 3, 6, 15, 90, 1, 2, 1, 6, 5, 30, 7, 14, 21, 42, 315, 630, 1, 2, 1, 6, 5, 30, 1, 2, 1, 6, 1, 6, 5, 10, 15, 30, 15, 90, 25, 50, 25, 150, 25, 150, 175, 350, 525, 1050, 7875, 15750, 25, 50, 25, 150, 125, 750
Offset: 0

Views

Author

Antti Karttunen, Nov 07 2021

Keywords

Crossrefs

Programs

  • PARI
    A349000(n) = { my(m1=1, m2=1, p=2, u); while(n, if(n%p, u = p^(n%p); m1 *= u; m2 *= (1+u)); n = n\p; p = nextprime(1+p)); gcd(m1,m2); };

Formula

a(n) = A323166(A276086(n)) = gcd(A276086(n), A348996(n)).
Showing 1-5 of 5 results.