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 1-3 of 3 results.

A085563 Sum of the prime digits of n.

Original entry on oeis.org

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

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Author

Jason Earls, Jul 05 2003

Keywords

Examples

			a(1234567)=17 because 2+3+5+7=17.
		

Crossrefs

Programs

  • Mathematica
    Table[Total[Select[IntegerDigits[n],PrimeQ]],{n,110}] (* Harvey P. Dale, Aug 15 2020 *)
  • PARI
    a(n) = vecsum(select(isprime, digits(n))); \\ Michel Marcus, Feb 06 2021

Formula

a(n)+A085562(n) = A007953(n). [R. J. Mathar, Aug 04 2008]

A341013 The cumulative sum of the prime digits so far in the sequence and the cumulative sum of the nonprime digits so far differ by n for all a(n) values.

Original entry on oeis.org

1, 3, 12, 16, 10, 34, 43, 56, 65, 78, 87, 100, 236, 258, 263, 285, 304, 326, 340, 359, 362, 395, 403, 430, 447, 474, 506, 528, 539, 560, 582, 593, 605, 623, 632, 650, 708, 744, 780, 807, 825, 852, 870, 935, 953, 1000, 1112, 1121, 1145, 1154, 1167, 1176
Offset: 1

Views

Author

Carole Dubois and Eric Angelini, Feb 02 2021

Keywords

Comments

The prime digits are 2, 3, 5 and 7; the nonprime digits are 0, 1, 4, 6, 8 and 9.
This is the lexicographically earliest sequence of distinct integers > 0 having this property.

Examples

			Say that the current sequence is S, the cumulative sum at any moment of the prime digits of S is P, the cumulative sum at any moment of the nonprime digits of S is N and the absolute difference |P-N| is D. We would then have:
S =  1, 3, 12, 16, 10, 34, 43, 56, 65, 78, 87, 100,...
P =  0  3   5   5   5   8  11  16  21  28  35   35
N =  1  1   2   9  10  14  18  24  30  38  46   47
D =  1  2   3   4   5   6   7   8   9  10  11   12 <-- this is = n
		

Crossrefs

Cf. A341012 (the cumulative sums of even vs odd digits differ by n).

A341161 The sum of the prime digits of m and the sum of the nonprime digits of m differ by n.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 19, 119, 48, 49, 68, 69, 88, 89, 99, 199, 488, 489, 499, 689, 699, 889, 899, 999, 1999, 4889, 4899, 4999, 6899, 6999, 8899, 8999, 9999, 19999, 48899, 48999, 49999, 68999, 69999, 88999, 89999, 99999, 199999, 488999
Offset: 1

Views

Author

Carole Dubois and Eric Angelini, Feb 06 2021

Keywords

Comments

This is the lexicographically earliest sequence of distinct terms > 0 with this property.
The nonprime digits are 0, 1, 4, 6, 8 and 9; the prime digits are 2, 3, 5 and 7. After a(7) = 7 no more terms will show a prime digit.

Examples

			The sequence:     1, 2, 3, 4, 5, 6, 7, 8, 9, 19, 119, 48,...
Sum of prime dig. 0  2  3  0  5  0  7  0  0   0    0   0
Sum of nonprimes  1  0  0  4  0  6  0  8  9  10   11  12
Difference (= n)  1  2  3  4  5  6  7  8  9  10   11  12
		

Crossrefs

Showing 1-3 of 3 results.