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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A369647 Nonzero numbers k in A341518 for which A051903(k) attains novel values.

Original entry on oeis.org

1, 2, 9, 16, 108, 9024, 2990880, 995336192, 1805726080
Offset: 1

Views

Author

Antti Karttunen, Feb 02 2024

Keywords

Comments

Indices of record values of A051903 attained for the terms of A341518 is a subsequence: 1, 2, 9, 16, 9024, 995336192.

Examples

			           k   factorization           max.exp         k'    A049345(k')
           1                              0,           0,            0
           2 = 2^1,                       1,           1,            1
           9 = 3^2,                       2,           6,          100
          16 = 2^4,                       4,          32,         1010
         108 = 2^2 * 3^3,                 3,         216,        10100
        9024 = 2^6 * 3 * 47,              6,       30272,      1011010
     2990880 = 2^5 * 3^2 * 5 * 31 * 67,   5,    10210416,    110010100
   995336192 = 2^13 * 121501,            13,  6469693440,  10000010000
  1805726080 = 2^7 * 5 * 157 * 17971,     7,  6692788416,  11000100100.
See also the examples at A351073 and A369649.
		

Crossrefs

Programs

  • PARI
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A051903(n) = if((1==n),0,vecmax(factor(n)[, 2]));
    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); };
    isA341518(n) = ismaxprimobasedigit_at_most(A003415(n),1);
    m=Map(); for(n=1,2990880,if(isA341518(n),e=A051903(n);if(!mapisdefined(m,e),mapput(m,e,n);print1(n,", "))));

A369648 Indices of novel terms in A351073, where A351073 is the maximal exponent in the prime factorization of the numbers that are sums of distinct primorial numbers.

Original entry on oeis.org

1, 2, 6, 7, 10, 24, 90, 144, 766, 1040, 1164, 2122, 3010, 8914, 17838, 20500, 87472, 243252, 312058, 1118346, 1347998, 2167146, 3569780, 6038946
Offset: 1

Views

Author

Antti Karttunen, Feb 03 2024

Keywords

Comments

Indices k at which A351073(k) for the first time attains a new distinct value.

Examples

			See examples in A369649.
		

Crossrefs

Cf. A002110, A051903, A276156, A351073, A369649 (corresponding values of A276156).
Cf. also A369647.

Programs

  • 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));
    m=Map(); for(n=1,2^25,e=A351073(n);if(!mapisdefined(m,e),mapput(m,e,n);print1(n,", ")));
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