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.

Previous Showing 11-20 of 20 results.

A329344 Number of times most frequent primorial is present in the greedy sum of primorials adding to A108951(n).

Original entry on oeis.org

1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 4, 1, 2, 6, 2, 1, 2, 1, 4, 6, 2, 1, 3, 4, 2, 1, 4, 1, 5, 1, 1, 6, 2, 8, 4, 1, 2, 6, 1, 1, 1, 1, 4, 5, 2, 1, 3, 6, 8, 6, 4, 1, 2, 4, 8, 6, 2, 1, 3, 1, 2, 3, 2, 13, 12, 1, 4, 6, 5, 1, 3, 1, 2, 5, 4, 16, 12, 1, 2, 6, 2, 1, 2, 11, 2, 6, 8, 1, 10, 12, 4, 6, 2, 7, 6, 1, 12, 10, 6, 1, 12, 1, 8, 4
Offset: 1

Views

Author

Antti Karttunen, Nov 11 2019

Keywords

Comments

The greedy sum is also the sum with the minimal number of primorials, used for example in the primorial base representation.

Examples

			For n = 24 = 2^3 * 3, A108951(24) = A034386(2)^3 * A034386(3) = 2^3 * 6 = 48 = 30 + 6 + 6 + 6, and as the most frequent primorial in the sum is 6 = A002110(2), we have a(24) = 3.
		

Crossrefs

Programs

  • Mathematica
    With[{b = Reverse@ Prime@ Range@ 120}, Array[Max@ IntegerDigits[#, MixedRadix[b]] &@ Apply[Times, Map[#1^#2 & @@ # &, FactorInteger[#] /. {p_, e_} /; e > 0 :> {Times @@ Prime@ Range@ PrimePi@ p, e}]] &, 105] ] (* Michael De Vlieger, Nov 18 2019 *)
  • PARI
    A034386(n) = prod(i=1, primepi(n), prime(i));
    A108951(n) = { my(f=factor(n)); prod(i=1, #f~, A034386(f[i, 1])^f[i, 2]) };  \\ From A108951
    A328114(n) = { my(s=0, p=2); while(n, s = max(s,(n%p)); n = n\p; p = nextprime(1+p)); (s); };
    A329344(n) = A328114(A108951(n));
    
  • PARI
    A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
    A324886(n) = A276086(A108951(n));
    A051903(n) = if((1==n),0,vecmax(factor(n)[, 2]));
    A329344(n) = A051903(A324886(n));

Formula

a(n) = A328114(A108951(n)) = A051903(A324886(n)).

A328771 Minimal number of primorials (A002110) that add to A328768(n), where A328768 is the first primorial based variant of arithmetic derivative.

Original entry on oeis.org

0, 0, 1, 1, 2, 1, 2, 1, 2, 2, 5, 1, 4, 1, 4, 6, 2, 1, 3, 1, 4, 6, 6, 1, 6, 2, 5, 5, 10, 1, 6, 1, 6, 8, 7, 8, 6, 1, 6, 8, 6, 1, 5, 1, 8, 7, 8, 1, 6, 2, 9, 6, 10, 1, 8, 8, 8, 6, 9, 1, 10, 1, 4, 9, 8, 10, 13, 1, 8, 8, 14, 1, 10, 1, 5, 5, 10, 12, 10, 1, 6, 2, 7, 1, 8, 10, 6, 10, 14, 1, 5, 14, 8, 6, 8, 12, 6, 1, 9, 15, 8, 1, 16, 1, 14, 7
Offset: 0

Views

Author

Antti Karttunen, Oct 28 2019

Keywords

Crossrefs

Programs

  • PARI
    A002110(n) = prod(i=1,n,prime(i));
    A328768(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]*A002110(primepi(f[i,1])-1)/f[i, 1]));
    A276150(n) = { my(s=0, p=2, d); while(n, d = (n%p); s += d; n = (n-d)/p; p = nextprime(1+p)); (s); };
    A328771(n) = A276150(A328768(n));

Formula

a(n) = A276150(A328768(n)).

A342462 Sum of digits when A329886(n) is written in primorial base, where A329886 is the primorial inflation of Doudna-tree.

Original entry on oeis.org

1, 1, 1, 2, 1, 2, 2, 2, 1, 2, 6, 4, 6, 4, 2, 4, 1, 2, 6, 4, 10, 6, 6, 4, 8, 12, 10, 8, 22, 4, 8, 2, 1, 2, 6, 4, 6, 2, 6, 2, 18, 10, 8, 6, 18, 12, 16, 4, 26, 16, 24, 8, 20, 14, 4, 6, 26, 16, 14, 8, 30, 6, 8, 4, 1, 2, 6, 4, 14, 12, 12, 8, 18, 12, 24, 4, 8, 12, 14, 4, 24, 20, 28, 20, 26, 16, 16, 12, 32, 26, 24, 14, 28, 16
Offset: 0

Views

Author

Antti Karttunen, Mar 15 2021

Keywords

Comments

From David A. Corneth's Feb 27 2019 comment in A276150 follows that the only odd terms in this sequence are 1's occurring at 0 and at two's powers.
Subsequences starting at each n = 2^k are slowly converging towards A329886: 1, 2, 6, 4, 30, 12, 36, 8, 210, 60, 180, 24, etc.. Compare also to the behaviors of A324342 and A342463.

Crossrefs

Programs

Formula

a(n) = A001222(A342456(n)) = A001222(A342457(n)).
a(n) = A276150(A329886(n)) = A324888(A005940(1+n)).
a(n) >= A342461(n).
For n >= 0, a(2^n) = 1.

A329349 Number of occurrences of the largest primorial present in the greedy sum of primorials adding to A108951(n).

Original entry on oeis.org

1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 4, 1, 2, 6, 2, 1, 2, 1, 4, 6, 2, 1, 1, 4, 2, 1, 4, 1, 1, 1, 1, 6, 2, 2, 4, 1, 2, 6, 1, 1, 1, 1, 4, 5, 2, 1, 3, 1, 8, 6, 4, 1, 2, 2, 8, 6, 2, 1, 3, 1, 2, 3, 2, 1, 12, 1, 4, 6, 5, 1, 1, 1, 2, 2, 4, 16, 12, 1, 2, 6, 2, 1, 2, 1, 2, 6, 8, 1, 10, 12, 4, 6, 2, 1, 6, 1, 2, 2, 1, 1, 12, 1, 8, 1
Offset: 1

Views

Author

Antti Karttunen, Nov 11 2019

Keywords

Comments

The greedy sum is also the sum with the minimal number of primorials, used for example in the primorial base representation.

Examples

			For n = 21 = 3 * 7, A108951(21) = A034386(3) * A034386(7) = 6 * 210, so the factor of the largest primorial present (210) in the greedy sum is 6 (as 1260 = 210 + 210 + 210 + 210 + 210 + 210), thus a(21) = 6.
For n = 24 = 2^3 * 3, A108951(24) = A034386(2)^3 * A034386(3) = 2^3 * 6 = 48 = 1*30 + 3*6, and as the factor of the largest primorial in the sum is 1, we have a(24) = 1.
		

Crossrefs

Programs

Formula

a(n) = A276153(A108951(n)) = A071178(A324886(n)).
a(n) <= A324888(n).

A324905 a(n) = A007895(A003965(n)).

Original entry on oeis.org

1, 1, 1, 2, 1, 2, 1, 1, 2, 2, 1, 3, 1, 2, 2, 2, 1, 2, 1, 3, 2, 2, 1, 2, 3, 2, 3, 3, 1, 3, 1, 3, 2, 2, 3, 2, 1, 2, 2, 3, 1, 3, 1, 3, 3, 2, 1, 3, 3, 3, 2, 3, 1, 4, 3, 3, 2, 2, 1, 2, 1, 2, 4, 3, 3, 3, 1, 3, 2, 4, 1, 4, 1, 2, 4, 3, 3, 3, 1, 4, 3, 2, 1, 3, 3, 2, 2, 3, 1, 2, 3, 3, 2, 2, 3, 3, 1, 3, 4, 3, 1, 3, 1, 3, 4
Offset: 1

Views

Author

Antti Karttunen, Apr 14 2019

Keywords

Crossrefs

Programs

  • PARI
    A003965(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1] = fibonacci(2+primepi(f[i, 1]))); factorback(f); };
    A007895(n) = { my(s=0); while(n>0, s++; n -= fibonacci(1+A072649(n))); (s); }
    A072649(n) = { my(m); if(n<1, 0, m=0; until(fibonacci(m)>n, m++); m-2); }; \\ From A072649
    A324905(n) = A007895(A003965(n));

Formula

a(n) = A007895(A003965(n)).

A324907 a(n) = A007895(A113175(n)).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 1, 3, 1, 1, 1, 1, 2, 1, 1, 2, 1, 3, 2, 1, 1, 2, 1, 1, 2, 1, 1, 3, 1, 1, 1, 4, 3, 2, 1, 1, 1, 3, 1, 2, 1, 1, 2, 1, 1, 3, 1, 3, 2, 1, 1, 2, 3, 1, 2, 1, 1, 3, 1, 4, 2, 1, 1, 2, 1, 1, 2, 3, 1, 2, 1, 1, 3, 4, 1, 2, 1, 3, 1, 1, 4, 3, 3, 1, 2, 1, 1, 4
Offset: 1

Views

Author

Antti Karttunen, Apr 14 2019

Keywords

Crossrefs

Programs

  • PARI
    A113175(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1] = fibonacci(f[i, 1])); factorback(f); };
    A007895(n) = { my(s=0); while(n>0, s++; n -= fibonacci(1+A072649(n))); (s); }
    A072649(n) = { my(m); if(n<1, 0, m=0; until(fibonacci(m)>n, m++); m-2); }; \\ From A072649
    A324907(n) = A007895(A113175(n));

Formula

a(n) = A007895(A113175(n)).
a(2n) = a(n).

A324887 a(n) = A108951(n) * A276086(A108951(n)).

Original entry on oeis.org

2, 6, 30, 36, 210, 300, 2310, 120, 1260, 2940, 30030, 15000, 510510, 50820, 21176820, 3600, 9699690, 88200, 223092870, 288120, 2232166860, 780780, 6469693230, 42000, 645668100, 17357340, 11880, 12298440, 200560490130, 66555720, 7420738134810, 672, 66899572740, 368588220, 228227900600700, 216090000, 304250263527210
Offset: 1

Views

Author

Antti Karttunen, Mar 30 2019

Keywords

Crossrefs

Programs

Formula

a(n) = A324580(A108951(n)) = A108951(n) * A324886(n).

A328772 Minimal number of primorials (A002110) that add to A328769(n), where A328769 is the second primorial based variant of arithmetic derivative.

Original entry on oeis.org

0, 0, 1, 1, 2, 1, 3, 1, 4, 2, 5, 1, 4, 1, 5, 4, 4, 1, 3, 1, 8, 6, 7, 1, 4, 4, 7, 7, 10, 1, 3, 1, 8, 6, 5, 6, 2, 1, 5, 8, 6, 1, 11, 1, 12, 3, 7, 1, 6, 4, 7, 8, 10, 1, 9, 10, 16, 10, 9, 1, 8, 1, 5, 13, 10, 12, 15, 1, 12, 10, 7, 1, 8, 1, 7, 5, 10, 8, 11, 1, 12, 6, 9, 1, 8, 10, 9, 12, 14, 1, 9, 10, 12, 10, 7, 12, 6, 1, 13, 17, 14, 1, 11, 1, 14, 9
Offset: 0

Views

Author

Antti Karttunen, Oct 28 2019

Keywords

Crossrefs

Programs

  • PARI
    A002110(n) = prod(i=1,n,prime(i));
    A328769(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]*A002110(primepi(f[i,1]))/f[i, 1]));
    A276150(n) = { my(s=0, p=2, d); while(n, d = (n%p); s += d; n = (n-d)/p; p = nextprime(1+p)); (s); };
    A328772(n) = A276150(A328769(n));

Formula

a(n) = A276150(A328769(n)).

A373989 a(n) = A276150(gcd(A108951(n), A373158(n))), where A276150 is the digit sum in primorial base, A108951 is fully multiplicative and A373158 is fully additive with a(p) = p# for prime p, where x# is the primorial A034386(x).

Original entry on oeis.org

1, 1, 1, 2, 1, 2, 1, 1, 2, 2, 1, 1, 1, 2, 2, 2, 1, 1, 1, 1, 2, 2, 1, 2, 2, 2, 3, 1, 1, 1, 1, 1, 2, 2, 2, 4, 1, 2, 2, 2, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 2, 6, 4, 2, 2, 1, 4, 1, 2, 1, 2, 6, 1, 1, 1, 2, 1, 1, 3, 1, 2, 1, 1, 6, 1, 1, 1, 4, 2, 1, 4, 2, 2, 2, 2, 1, 2, 6, 1, 2, 2, 2, 4, 1, 1, 5, 4, 1, 1, 1, 2, 1
Offset: 1

Views

Author

Antti Karttunen, Jun 26 2024

Keywords

Crossrefs

Programs

  • PARI
    A276150(n) = { my(s=0, p=2, d); while(n, d = (n%p); s += d; n = (n-d)/p; p = nextprime(1+p)); (s); };
    A373985(n) = { my(f=factor(n),m=1,s=0); for(i=1, #f~, my(x=prod(i=1,primepi(f[i, 1]),prime(i))); s += f[i, 2]*x; m *= x^f[i, 2]); gcd(m,s); };
    A373989(n) = A276150(A373985(n));

Formula

a(n) = A276150(A373985(n)).

A365461 Sum of digits when A181821(n) is written in primorial base (A049345).

Original entry on oeis.org

1, 1, 2, 1, 2, 2, 4, 1, 2, 4, 2, 2, 4, 4, 4, 1, 6, 6, 6, 4, 8, 4, 6, 2, 2, 8, 6, 2, 12, 6, 16, 1, 6, 10, 4, 6, 16, 10, 8, 4, 10, 6, 10, 4, 12, 10, 6, 2, 8, 6, 10, 8, 12, 10, 8, 8, 20, 10, 18, 2, 26, 14, 8, 1, 12, 12, 22, 10, 20, 12, 28, 6, 28, 14, 10, 10, 6, 8, 34, 4, 8, 18, 38, 4, 10, 14, 20, 6, 52, 10, 12, 10, 24
Offset: 1

Views

Author

Antti Karttunen, Sep 15 2023

Keywords

Comments

Minimal number of primorials (A002110) that add to A181821(n).

Crossrefs

Programs

  • PARI
    A181821(n) = { my(f=factor(n),p=0,m=1); forstep(i=#f~,1,-1,while(f[i,2], f[i,2]--; m *= (p=nextprime(p+1))^primepi(f[i,1]))); (m); };
    A276150(n) = { my(s=0, p=2, d); while(n, d = (n%p); s += d; n = (n-d)/p; p = nextprime(1+p)); (s); };
    A365461(n) = A276150(A181821(n));

Formula

a(n) = A276150(A181821(n)).
a(n) = A324888(A122111(n)).
a(n) >= A365460(n).
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