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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A328405 The length of primorial base expansion (number of significant digits) of A276086(A276086(n)), where A276086(n) converts primorial base expansion of n into its prime product form.

Original entry on oeis.org

2, 2, 3, 2, 4, 4, 3, 4, 4, 3, 5, 5, 5, 6, 6, 6, 5, 5, 7, 6, 9, 8, 10, 14, 11, 12, 14, 12, 12, 15, 3, 4, 5, 4, 5, 6, 4, 5, 7, 3, 8, 5, 9, 9, 8, 7, 12, 7, 8, 12, 8, 7, 12, 14, 16, 15, 15, 15, 11, 12, 5, 6, 8, 7, 7, 8, 5, 7, 9, 9, 14, 12, 12, 9, 12, 7, 15, 15, 12, 12, 18, 13, 20, 17, 11, 13, 15, 14, 17, 13, 8, 9, 11, 14, 11, 13, 11, 10, 10, 10
Offset: 0

Views

Author

Antti Karttunen, Oct 16 2019

Keywords

Crossrefs

Programs

  • Mathematica
    Block[{b = MixedRadix[Reverse@ Prime@ Range@ 120], f}, f[n_] := Times @@ Power @@@ # &@ Transpose@ {Prime@ Range@ Length@ #, Reverse@ #} &@ IntegerDigits[n, b]; Array[IntegerLength[Nest[f, #, 2], b] &, 100, 0]] (* Michael De Vlieger, Oct 17 2019 *)
  • PARI
    A235224(n) = { my(s=0, p=2); while(n, s++; n = n\p; p = nextprime(1+p)); (s); };
    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));
    A328405(n) = A235224(A276087(n));

Formula

a(n) = A235224(A276087(n)) = A061395(A328403(n)).
For all n, A000040(a(n)) > A328394(n).

A328579 a(n) = A053669(A276086(A276086(n))).

Original entry on oeis.org

3, 2, 5, 2, 7, 2, 5, 2, 7, 2, 11, 2, 3, 2, 11, 2, 7, 2, 5, 2, 13, 2, 13, 2, 3, 2, 13, 2, 17, 2, 3, 2, 7, 2, 5, 2, 5, 2, 11, 2, 13, 2, 3, 2, 13, 2, 13, 2, 5, 2, 17, 2, 17, 2, 3, 2, 17, 2, 11, 2, 3, 2, 11, 2, 7, 2, 5, 2, 13, 2, 13, 2, 3, 2, 17, 2, 17, 2, 5, 2, 17, 2, 19, 2, 3, 2, 13, 2, 19, 2, 3, 2, 13, 2, 17, 2, 5, 2, 17, 2, 17, 2, 3, 2, 17, 2
Offset: 0

Views

Author

Antti Karttunen, Oct 20 2019

Keywords

Crossrefs

Programs

Formula

a(n) = A053669(A276087(n)).
a(n) = A326810(A276086(n)).
a(n) = A000040(A328578(n)).
For all even n, a(n) > A328569(n).

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

Views

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));

A328633 Numbers n for which A328578(n) = A257993(A276086(A276086(n))) = 3, where A276086 converts the primorial base expansion of n into its prime product form, and A257993 returns the index of the least prime not present in its argument.

Original entry on oeis.org

2, 6, 18, 34, 36, 48, 66, 78, 96, 108, 122, 126, 138, 154, 156, 168, 186, 198, 212, 222, 234, 244, 252, 264, 282, 294, 312, 324, 332, 342, 354, 364, 372, 384, 402, 414, 422, 426, 438, 454, 456, 468, 486, 498, 516, 528, 542, 546, 558, 574, 576, 588, 606, 618, 632, 642, 654, 664, 672, 684, 702, 714, 732, 744, 752, 762, 774, 784, 792, 804
Offset: 1

Views

Author

Antti Karttunen, Oct 27 2019

Keywords

Comments

Numbers n for which A276087(n) is a multiple of 6, but not of 5.
Question: Is the even bisection of A328316, starting from A328316(4) as: 6, 18, 43218, ..., a subsequence of this sequence? See also A328317.
Subsequence such that both k and A276087(k) are in this sequence starts as: 2, 6, 18, 34, 36, 48, 66, 154, 156, 186, 234, 244, 294, 312, 324, 354, 364, 384, 426, 438, 454, 456, 542, 546, 558, 588, 606, ...
When A276086 is applied to any number which is a multiple of 6, but not of 5 (and thus not a multiple of 30, implying that the number's primorial expansion ends with "x00", where x <> 0, and A257993(n) = 3), the original number will be converted to a number of the form 30k+5 or 30k+25 (A084967) whose primorial expansion ends either as "...021" or as "...401", with the least significant zero in position A328578(n), which is seen to be always either 3 or 2.

Examples

			294 = 7^2 * 3 * 2 has primorial base expansion (A049345) "12400", which, when converted to a prime product form (A276086) yields 11^1 * 7^2 * 5^4 * 3^0 * 2^0 = 336875. This in turn has primorial base representation [11,2,9,1,0,2,1], which when converted to prime product form gives 17^11 * 13^2 * 11^9 * 7^1 * 5^0 * 3^2 * 2^1 = 1720796647657111567992931482, which has the required property of being a multiple of 6 but not of 5, thus 294 is included in this sequence.
		

Crossrefs

Programs

A328569 Exponent of least prime factor in A276086(A276086(n)), where A276086 converts the primorial base expansion of n into its prime product form.

Original entry on oeis.org

1, 1, 1, 1, 1, 3, 1, 2, 1, 1, 1, 3, 1, 1, 1, 5, 1, 1, 1, 2, 1, 4, 1, 5, 1, 1, 1, 6, 1, 4, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 3, 1, 1, 1, 5, 1, 4, 1, 2, 1, 3, 1, 9, 1, 1, 1, 4, 1, 1, 1, 1, 1, 4, 1, 2, 1, 2, 1, 7, 1, 10, 1, 1, 1, 2, 1, 6, 1, 2, 1, 10, 1, 8, 1, 1, 1, 6, 1, 7, 1, 1, 1, 3, 1, 4, 1, 2, 1, 5, 1, 4, 1, 1, 1, 3
Offset: 0

Views

Author

Antti Karttunen, Oct 20 2019

Keywords

Comments

Equally, the least significant nonzero digit in primorial base expansion of A276086(n).

Crossrefs

Programs

  • PARI
    A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
    A276088(n) = { my(e=0, p=2); while(n && !(e=(n%p)), n = n/p; p = nextprime(1+p)); (e); };
    A328569(n) = A276088(A276086(n));

Formula

a(n) = A276088(A276086(n)) = A067029(A276087(n)).
max(a(n),1+A051903(A328400(A003557(A276086(A328476(n)))))) = A328389(n). [A328400 is optional in the formula]
For all even n, a(n) < A328579(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]

A328829 Index of the least significant digit > 1 in the primorial base expansion of A276086(n), 0 if no such digit exists.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Oct 29 2019

Keywords

Comments

a(n) = index of the least non-unitary prime divisor of A276087(n) or 0 if no such prime-divisor exists.

Crossrefs

Cf. A276086, A276087, A277885, A328828, A328836 (positions of zeros).

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); };
    A328829(n) = A328828(A276086(n));
    
  • PARI
    A277885(n) = if(1==n,0,my(f=factor(n)); for(i=1,#f~,if(f[i,2]>1,return(primepi(f[i,1])))); (0));
    A328829(n) = A277885(A276086(A276086(n)));

Formula

a(n) = A328828(A276086(n)) = A277885(A276087(n)).

A328634 Numbers n for which A328578(n) = A257993(A276086(A276086(n))) = 4.

Original entry on oeis.org

4, 8, 16, 32, 64, 152, 184, 210, 242, 274, 362, 394, 440, 448, 452, 484, 572, 604, 634, 638, 646, 662, 694, 782, 814, 872, 904, 992, 1024, 1070, 1078, 1082, 1114, 1202, 1234, 1264, 1268, 1276, 1292, 1324, 1412, 1444, 1470, 1502, 1534, 1622, 1654, 1700, 1708, 1712, 1744, 1832, 1864, 1894, 1898, 1906, 1922, 1954, 2042
Offset: 1

Views

Author

Antti Karttunen, Oct 27 2019

Keywords

Comments

Numbers n for which A276087(n) is a multiple of 30, but not of 7.

Crossrefs

Row 4 of A328631.

Programs

A328635 Numbers n for which A328578(n) = A257993(A276086(A276086(n))) = 5.

Original entry on oeis.org

10, 14, 38, 58, 62, 112, 166, 176, 214, 218, 226, 240, 360, 650, 658, 660, 780, 844, 848, 856, 1080, 1200, 1280, 1288, 1474, 1478, 1486, 1500, 1620, 1910, 1918, 1920, 2040, 2104, 2108, 2116, 2312, 2314, 2318, 2386, 2396, 2440, 2450, 2504, 2520, 2546, 2580, 2700, 2732, 2744, 2752, 2950, 3000, 3120, 3176, 3362, 3374, 3382, 3420
Offset: 1

Views

Author

Antti Karttunen, Oct 27 2019

Keywords

Comments

Numbers n for which A276087(n) is a multiple of 210, but not of 11.

Crossrefs

Row 5 of A328631.

Programs

A328636 Numbers n for which A328578(n) = A257993(A276086(A276086(n))) = 6.

Original entry on oeis.org

20, 22, 26, 40, 44, 46, 68, 70, 86, 92, 220, 224, 238, 248, 270, 272, 286, 356, 370, 424, 428, 500, 538, 544, 584, 622, 630, 682, 728, 766, 836, 896, 910, 934, 980, 1018, 1124, 1162, 1208, 1230, 1232, 1246, 1306, 1376, 1390, 1460, 1520, 1558, 1604, 1642, 1706, 1748, 1786, 1856, 1870, 1930, 2000, 2038, 2084, 2144, 2182, 2228, 2266
Offset: 1

Views

Author

Antti Karttunen, Oct 27 2019

Keywords

Comments

Numbers n for which A276087(n) is a multiple of 2310, but not of 13.

Crossrefs

Row 6 of A328631.

Programs

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