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.

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A328836 Numbers k such that A276086(k) is a sum of distinct primorial numbers.

Original entry on oeis.org

0, 1, 2, 3, 4, 9, 30, 39, 212, 249, 421, 2312, 2559, 30045, 32589, 510511, 512820, 543099, 1021050, 9729723, 10242789, 233335659, 446185742
Offset: 1

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Author

Antti Karttunen, Oct 29 2019

Keywords

Comments

Numbers k such that A276086(k) is in A276156, i.e., numbers k for which A328828(A276086(k)) is zero, i.e., numbers k such that in the primorial base expansion of A276086(k) there are no digits larger than 1.
Numbers k for which A276087(k) is squarefree.
No more terms below 2^31.

Crossrefs

Sequence A328833 sorted into ascending order.
Positions of zeros in A328829 and in A328844, positions of ones in A328389.
Cf. A143293 (a subsequence).
All the terms of A328313 are included in this sequence, like also in A328837.

Programs

  • PARI
    A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
    A328828(n) = { my(i=1, p=2); while(n, if((n%p)>1, return(i)); i++; n = n\p; p = nextprime(1+p)); (0); };
    isA328836(n) = !A328828(A276086(n));

A346105 a(n) = A276085(A108951(n)).

Original entry on oeis.org

0, 1, 3, 2, 9, 4, 39, 3, 6, 10, 249, 5, 2559, 40, 12, 4, 32589, 7, 543099, 11, 42, 250, 10242789, 6, 18, 2560, 9, 41, 233335659, 13, 6703028889, 5, 252, 32590, 48, 8, 207263519019, 543100, 2562, 12, 7628001653829, 43, 311878265181039, 251, 15, 10242790, 13394639596851069, 7, 78, 19, 32592, 2561, 628284422185342479, 10, 258, 42
Offset: 1

Views

Author

Antti Karttunen, Jul 08 2021

Keywords

Comments

Additive with a(p^e) = e * A143293(A000720(p)-1), where A143293 is the partial sums of primorials, A002110. (Compare to the formula of A276085).

Crossrefs

Programs

  • PARI
    A002110(n) = prod(i=1,n,prime(i));
    A108951(n) = { my(f=factor(n)); prod(i=1, #f~, A002110(primepi(f[i, 1]))^f[i, 2]) };
    A276085(n) = { my(f = factor(n)); sum(k=1, #f~, f[k, 2]*A002110(primepi(f[k, 1])-1)); };
    A346105(n) = A276085(A108951(n));
    
  • PARI
    A143293(n) = { if(n==0, return(1)); my(P=1, s=1); forprime(p=2, prime(n), s+=P*=p); s; }; \\ This function from A143293
    A346105(n) = { my(f = factor(n)); sum(k=1, #f~, f[k, 2]*A143293(primepi(f[k, 1])-1)); };

Formula

a(n) = A276085(A108951(n)).

A351073 Maximal exponent in the prime factorization of A276156(n).

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Feb 03 2022

Keywords

Comments

See also comments in A143293.

Examples

			For n = 1040 = 2^10 + 2^4, A276156(n) = A002110(10) + A002110(4) = 6469693440 = 2^12 * 3 * 5 * 7^3 * 307. The largest exponent is 12, therefore a(1040) = 12.
		

Crossrefs

Programs

  • Mathematica
    {0}~Join~Array[Max[FactorInteger[#][[All, -1]]] &@ Total[Times @@@ Transpose@{Map[Times @@ # &, Prime@ Range@ Range[0, Length@ # - 1]], Reverse@ #}] &@ IntegerDigits[#, 2] &, 104, 2] (* Michael De Vlieger, Feb 04 2022 *)
  • PARI
    A051903(n) = if((1==n),0,vecmax(factor(n)[, 2]));
    A276156(n) = { my(s=0, p=1, r=1); while(n, if(n%2, s += r); n>>=1; p = nextprime(1+p); r *= p); (s); };
    A351073(n) = A051903(A276156(n));

Formula

a(n) = A051903(A276156(n)).
For n >= 1, a(2^n) = 1.

A328462 Numbers obtained by reinterpreting base-2 representation of odd numbers in primorial base.

Original entry on oeis.org

1, 3, 7, 9, 31, 33, 37, 39, 211, 213, 217, 219, 241, 243, 247, 249, 2311, 2313, 2317, 2319, 2341, 2343, 2347, 2349, 2521, 2523, 2527, 2529, 2551, 2553, 2557, 2559, 30031, 30033, 30037, 30039, 30061, 30063, 30067, 30069, 30241, 30243, 30247, 30249, 30271, 30273, 30277, 30279, 32341, 32343, 32347, 32349, 32371, 32373
Offset: 1

Views

Author

Antti Karttunen, Oct 16 2019

Keywords

Crossrefs

Row 1 of A328464, odd bisection of A276156 and of A328461.
Cf. A143293 (subsequence).

Programs

  • PARI
    A276156(n) = { my(p=2,pr=1,s=0); while(n,if(n%2,s += pr); n >>= 1; pr *= p; p = nextprime(1+p)); (s); };
    A328462(n) = A276156(n+n-1);

A370132 Numbers with no digit larger than 2 in primorial base, A049345.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 240, 241, 242, 243
Offset: 1

Views

Author

Antti Karttunen, Feb 10 2024

Keywords

Comments

Numbers k for which A328114(k) <= 2.
Numbers k such that A276086(k) is cubefree (in A004709).

Crossrefs

Subsequence of A370133.
Subsequences: A328242, A276156 and its subsequences: A002110, A143293.

Programs

  • Mathematica
    q[n_] := Module[{k = n, p = 2, s = {}, r}, While[{k, r} = QuotientRemainder[k, p]; k != 0 || r != 0, AppendTo[s, r]; p = NextPrime[p]]; Count[s, ?(# > 2 &)] == 0]; Select[Range[0, 250], q] (* _Amiram Eldar, Mar 06 2024 *)
  • PARI
    ismaxprimobasedigit_at_most(n,k) = { my(s=0, p=2); while(n, if((n%p)>k, return(0)); n = n\p; p = nextprime(1+p)); (1); };
    isA370132(n) = ismaxprimobasedigit_at_most(n,2);

A376403 a(0) = 0, and for n > 0, a(n) = a(n-1) + A276076(a(n-1)), where A276076 is the factorial base exp-function.

Original entry on oeis.org

0, 1, 3, 9, 39, 1089, 520179, 1466909163669354042297
Offset: 0

Views

Author

Antti Karttunen, Nov 02 2024

Keywords

Comments

a(8) has 212 digits, a(9) has 10654 digits.
By induction, it is easy to see that formula a(n) = A276075(A376399(n)) implies that from the second term onward, this sequence gives the partial sums of A376399. See more comments in that sequence.

Crossrefs

Cf. also A143293 (when prepended with 0, an analogous sequence for A276086).

Programs

Formula

a(n) = A276075(A376399(n)).
a(0) = 0; and for n > 0, a(n) = a(n-1) + A376399(n-1) = Sum_{i=0..n-1} A376399(i).

A380527 Numbers k such that k is a multiple of A327860(k), where A327860 is the arithmetic derivative of the primorial base exp-function.

Original entry on oeis.org

1, 2, 6, 7, 8, 30, 36, 210, 2310, 2340, 2520, 2556, 30030, 30240, 32340, 510510, 510720, 540540, 9699690, 9699720, 9702000, 9729720, 10210200, 223092870, 223092900, 223093080, 223095180, 232792560, 6469693230, 6469693236, 6469693440, 6469695540, 6692786100
Offset: 1

Views

Author

Antti Karttunen, Feb 11 2025

Keywords

Comments

It is conjectured that only terms of A276156 occur here. If any term of A177711 is included, then it must be one of the terms of A381037.
a(34) > A143293(10).

Crossrefs

Subsequence of A381035. Conjectured to be a subsequence of A276156.
Subsequences: A002110, A328110.
Cf. also A177711, A351087, A381037.

Programs

  • PARI
    A327860(n) = { my(s=0, m=1, p=2, e); while(n, e = (n%p); m *= (p^e); s += (e/p); n = n\p; p = nextprime(1+p)); (s*m); };
    is_A380527(n) = !(n%A327860(n));

A328395 Lexicographically earliest infinite sequence such that a(i) = a(j) => A046523(A276087(i)) = A046523(A276087(j)) for all i, j.

Original entry on oeis.org

1, 1, 2, 1, 3, 4, 5, 5, 6, 1, 7, 4, 8, 9, 10, 11, 7, 5, 12, 7, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 2, 5, 9, 5, 6, 8, 6, 23, 24, 1, 25, 4, 26, 27, 28, 11, 29, 8, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 9, 9, 42, 12, 24, 12, 7, 43, 44, 45, 46, 47, 48, 27, 49, 33, 50, 35, 51, 52, 53, 54, 55, 56, 57, 58, 59, 20, 60, 61, 30, 27, 62, 63, 64, 65, 66, 15, 67, 68, 69, 8
Offset: 0

Views

Author

Antti Karttunen, Oct 15 2019

Keywords

Comments

Restricted growth sequence transform of function f(n) = A278226(A276086(n)) = A046523(A276086(A276086(n))).
For all i, j:
a(i) = a(j) => A328397(i) = A328397(j) => A328389(i) = A328389(j).

Crossrefs

Cf. A143293 (positions of 1's after the initial one).

Programs

  • PARI
    up_to = 32589;
    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]); };  \\ From A046523
    A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
    A276087(n) = A276086(A276086(n));
    v328395 = rgs_transform(vector(1+up_to, n, A046523(A276087(n-1))));
    A328395(n) = v328395[1+n];

A328766 Number of nonleading zeros in primorial base expansion of A276086(n).

Original entry on oeis.org

0, 1, 0, 2, 0, 2, 0, 1, 0, 3, 0, 3, 1, 1, 0, 3, 1, 3, 1, 1, 0, 3, 0, 3, 1, 1, 0, 3, 0, 3, 1, 1, 0, 2, 1, 2, 1, 1, 0, 4, 0, 4, 1, 1, 0, 4, 0, 4, 1, 1, 0, 4, 0, 4, 1, 1, 0, 4, 1, 4, 1, 1, 0, 2, 1, 2, 1, 1, 0, 4, 0, 4, 1, 2, 0, 4, 0, 4, 1, 1, 0, 4, 0, 4, 2, 2, 1, 4, 0, 4, 1, 1, 0, 2, 0, 2, 1, 1, 0, 4, 0, 5, 1, 1, 0, 4
Offset: 0

Views

Author

Antti Karttunen, Oct 28 2019

Keywords

Crossrefs

Programs

  • PARI
    A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
    A328620(n) = { my(s=0, p=2); while(n, s += (0==(n%p)); n = n\p; p = nextprime(1+p)); (s); };
    A328766(n) = A328620(A276086(n));

Formula

a(n) = A328620(A276086(n)) = A079067(A276087(n)).
a(n) = A001221(A328763(n)) - 1.
For all n >= 1, a(A143293(n-1)) = n. [Note however that these are not the first occurrences of each n, that is, A143293 does not give the indices of records]

A370130 a(n) = A369669(A276086(n)), where A369669 is the greatest common divisor of the first and second arithmetic derivative of n, and A276086 is the primorial base exp-function.

Original entry on oeis.org

0, 1, 1, 1, 1, 1, 1, 1, 4, 1, 1, 1, 1, 3, 1, 1, 16, 1, 5, 5, 5, 5, 5, 5, 100, 25, 25, 175, 25, 25, 1, 3, 1, 1, 1, 1, 4, 1, 1, 1, 1, 1, 1, 1, 4, 17, 1, 1, 5, 5, 5, 5, 20, 5, 25, 25, 25, 25, 325, 25, 1, 1, 1, 1, 4, 1, 1, 1, 1, 1, 11, 1, 4, 1, 1, 1, 1, 1, 5, 5, 320, 95, 5, 5, 25, 25, 25, 25, 100, 25, 7, 7, 112, 7, 7, 7, 7, 7, 7, 7, 28
Offset: 0

Views

Author

Antti Karttunen, Feb 10 2024

Keywords

Crossrefs

Programs

Formula

a(n) = A369669(A276086(n)).
a(n) = gcd(A327860(n), A370131(n)).
For n >= 1, a(n) = A085731(A327860(n)).
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