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.

A090431 Difference between sums of digits of n and n-th prime.

Original entry on oeis.org

-1, -1, -2, -3, 3, 2, -1, -2, 4, -10, -2, -7, -1, -2, -5, -1, -6, 2, -3, -6, -7, -12, -6, -11, -9, 6, 5, 2, 1, -2, -6, 0, -5, -6, -6, 2, -3, 1, -2, -7, -12, -4, -4, -5, -8, -9, 7, 5, 2, -8, -2, -7, 1, 1, -4, 0, -5, 3, -2, -5, -6, -6, -1, 5, 4, 1, 6, 1, 1, -9, -3, -8, -6, -2
Offset: 1

Views

Author

Reinhard Zumkeller, Dec 01 2003

Keywords

Comments

a(n) = A007953(n) - A007605(n);
a(A033549(n))=a(A049084(A033548(n)))=0; a(A049084(A090432(n)))<0; a(A049084(A090433(n)))>0.

Crossrefs

Cf. A239324 (partial sums).

Programs

A090457 Primes prime(k) having fewer binary 1's than k.

Original entry on oeis.org

17, 257, 277, 293, 307, 401, 449, 577, 641, 643, 653, 673, 677, 709, 1031, 1033, 1039, 1091, 1093, 1129, 1153, 1217, 1297, 1409, 1543, 1553, 1601, 1607, 1609, 1613, 2053, 2063, 2081, 2083, 2087, 2089, 2099, 2113, 2179, 2309, 2341, 2371, 2593, 2609, 2633, 2647
Offset: 1

Views

Author

Reinhard Zumkeller, Dec 01 2003

Keywords

Crossrefs

Programs

  • Mathematica
    seq[len_] := Module[{s = {}, p = 2, k = 1, c = 0}, While[c < len, If[Greater @@ DigitCount[{k, p}, 2, 1], c++; AppendTo[s, p]]; k++; p = NextPrime[p]]; s]; seq[50] (* Amiram Eldar, Jul 18 2023 *)
    Prime[#]&/@Select[Range[500],DigitCount[#,2,1]>DigitCount[Prime[#],2,1]&] (* Harvey P. Dale, Apr 19 2024 *)
  • PARI
    isok(k) = hammingweight(prime(k)) < hammingweight(k);
    lista(nn) = for(n=1, nn, if (isok(n), print1(prime(n), ", "))); \\ Michel Marcus, Feb 05 2016

Formula

A090455(a(n)) > 0.

A090432 Primes prime(k) having a greater sum of digits than does k.

Original entry on oeis.org

2, 3, 5, 7, 17, 19, 29, 31, 37, 41, 43, 47, 53, 59, 67, 71, 73, 79, 83, 89, 97, 113, 127, 137, 139, 149, 157, 167, 173, 179, 181, 191, 193, 197, 199, 229, 233, 239, 257, 269, 277, 281, 283, 293, 307, 349, 353, 359, 367, 373, 379, 383, 389, 397, 409, 419, 439
Offset: 1

Views

Author

Reinhard Zumkeller, Dec 01 2003

Keywords

Comments

A090431(a(n)) < 0.

Crossrefs

Programs

  • Mathematica
    Prime[#]&/@Select[Range[100],Total[IntegerDigits[Prime[#]]]-Total[IntegerDigits[#]]>0&] (* Michel Lagneau, Nov 07 2015 *)
  • PARI
    isok(n) = sumdigits(prime(n)) > sumdigits(n); \\ Michel Marcus, Nov 07 2015
Showing 1-3 of 3 results.