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 1-8 of 8 results.

A175968 Complement of A175967(n), where A175967(n) = the lexicographically earliest sequence with first differences as increasing sequence of nonprimes A018252(n).

Original entry on oeis.org

3, 4, 5, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 24, 25, 26, 27, 28, 30, 31, 32, 33, 34, 35, 36, 37, 38, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79
Offset: 1

Views

Author

Jaroslav Krizek, Oct 31 2010

Keywords

Crossrefs

A014284 Partial sums of primes, if 1 is regarded as a prime (as it was until quite recently, see A008578).

Original entry on oeis.org

1, 3, 6, 11, 18, 29, 42, 59, 78, 101, 130, 161, 198, 239, 282, 329, 382, 441, 502, 569, 640, 713, 792, 875, 964, 1061, 1162, 1265, 1372, 1481, 1594, 1721, 1852, 1989, 2128, 2277, 2428, 2585, 2748, 2915, 3088, 3267, 3448, 3639, 3832, 4029
Offset: 1

Views

Author

Deepan Majmudar (dmajmuda(AT)esq.com)

Keywords

Comments

Lexicographically earliest sequence whose first differences are an increasing sequence of primes. Complement of A175969. - Jaroslav Krizek, Oct 31 2010
A175944(a(n)) = A018252(n). - Reinhard Zumkeller, Mar 18 2011
Partial sums of noncomposite numbers (A008578). - Omar E. Pol, Aug 09 2012

Examples

			a(7) = 42 because the first six primes (2, 3, 5, 7, 11, 13) add up to 41, and 1 + 41 = 42.
		

Crossrefs

Cf. A007504.
Equals A036439(n) - 1.
Cf. A008578.

Programs

Formula

a(n) = Sum_{k <= n} [(A158611(k + 1)) * (A000012(n - k + 1))] = Sum_{k <= n} [(A158611(k + 1)) * (A000012(k))] = Sum_{k <= n} [(A008578(k)) * (A000012(n - k + 1))] = Sum_{k <= n} [(A008578(k)) * (A000012(k))] for n, k >= 1. - Jaroslav Krizek, Aug 05 2009
a(n + 1) = A007504(n) + 1. a(n + 1) - a(n) = A000040(n) = n-th primes. - Jaroslav Krizek, Aug 19 2009
a(n) = a(n-1) + prime(n-1), with a(1)=1. - Vincenzo Librandi, Jul 27 2013
G.f: (x*(1+b(x)))/(1-x) = c(x)/(1-x), where b(x) and c(x) are respectively the g.f. of A000040 and A008578. - Mario C. Enriquez, Dec 10 2016

Extensions

Correction for Aug 2009 change of offset in A158611 and A008578 by Jaroslav Krizek, Jan 27 2010

A051349 Sum of first n nonprimes.

Original entry on oeis.org

0, 1, 5, 11, 19, 28, 38, 50, 64, 79, 95, 113, 133, 154, 176, 200, 225, 251, 278, 306, 336, 368, 401, 435, 470, 506, 544, 583, 623, 665, 709, 754, 800, 848, 897, 947, 998, 1050, 1104, 1159, 1215, 1272, 1330, 1390, 1452, 1515, 1579, 1644, 1710, 1778, 1847, 1917
Offset: 0

Views

Author

Armand Turpel (armandt(AT)unforgettable.com)

Keywords

Comments

Partial sums of A141468 or A018252. - R. J. Mathar, Mar 01 2009
The lexicographically earliest sequence with first differences as increasing sequence of composites A002808. Complement of A175970. See A175965, A175966, A175967, A014284, A175969, A175970. - Jaroslav Krizek, Oct 31 2010

Crossrefs

Programs

  • Maple
    ithnonprime := proc(n)local k: option remember: if(n=1)then return 1: fi: for k from procname(n-1)+1 do if(not isprime(k))then return k fi: od: end: A051349 := proc(n) option remember: local k: if(n<=1)then return n: fi: return ithnonprime(n)+procname(n-1): end: seq(A051349(n),n=0..51); # Nathaniel Johnston, May 25 2011
  • Mathematica
    lst={};s=0;Do[If[ !PrimeQ[n], s=s+n;AppendTo[lst, s]], {n, 0, 10^2}];lst (* Vladimir Joseph Stephan Orlovsky, Aug 14 2008 *)

Formula

Sum_{n>=1} 1/a(n) = A122998. - Amiram Eldar, Nov 17 2020

A175965 Lexicographically earliest sequence with first differences as increasing sequence of noncomposites A008578.

Original entry on oeis.org

1, 2, 4, 7, 12, 19, 30, 43, 60, 79, 102, 131, 162, 199, 240, 283, 330, 383, 442, 503, 570, 641, 714, 793, 876, 965, 1062, 1163, 1266, 1373, 1482, 1595, 1722, 1853, 1990, 2129, 2278, 2429, 2586, 2749, 2916, 3089, 3268, 3449, 3640, 3833, 4030, 4229, 4440, 4663
Offset: 1

Views

Author

Jaroslav Krizek, Oct 31 2010

Keywords

Comments

Complement of A175966.
A175944(a(n)) = A018252(n). - Reinhard Zumkeller, Mar 18 2011

Crossrefs

Programs

  • Haskell
    a175965 n = a175965_list !! n
    a175965_list = scanl (+) 1 a008578_list
    -- Reinhard Zumkeller, Mar 26 2015
  • Mathematica
    FoldList[Plus,1,Join[{1},Prime[Range[50]]]] (* or *) Accumulate[ Join[ {1,1},Prime[Range[50]]]] (* Harvey P. Dale, Sep 28 2016 *)

Formula

a(n) = A036439(n-1) for n > 1.
a(n) - a(n-1) = A008578(n-1) for n > 1.
a(n) = A014284(n-1) + 1 for n > 1.

A175966 Complement of A175965(n), where A175965(n) = the lexicographically earliest sequence with first differences as increasing sequence of noncomposites A008578.

Original entry on oeis.org

3, 5, 6, 8, 9, 10, 11, 13, 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 80
Offset: 1

Views

Author

Jaroslav Krizek, Oct 31 2010

Keywords

Crossrefs

A175969 Complement of A014284(n), where A014284(n) = the lexicographically earliest sequence with first differences as increasing sequence of primes A000040.

Original entry on oeis.org

2, 4, 5, 7, 8, 9, 10, 12, 13, 14, 15, 16, 17, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70
Offset: 1

Views

Author

Jaroslav Krizek, Oct 31 2010

Keywords

Crossrefs

A175970 Complement of A051349(n), where A051349(n) = the lexicographically earliest sequence with first differences as increasing sequence of composites A002808(n).

Original entry on oeis.org

2, 3, 4, 6, 7, 8, 9, 10, 12, 13, 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 26, 27, 29, 30, 31, 32, 33, 34, 35, 36, 37, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 65, 66, 67, 68, 69, 70
Offset: 1

Views

Author

Jaroslav Krizek, Oct 31 2010

Keywords

Crossrefs

A277375 Each nonprime integer "n" is followed by n prime integers.

Original entry on oeis.org

1, 2, 4, 3, 5, 7, 11, 6, 13, 17, 19, 23, 29, 31, 8, 37, 41, 43, 47, 53, 59, 61, 67, 9, 71, 73, 79, 83, 89, 97, 101, 103, 107, 10, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 12, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 14, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 15, 313
Offset: 1

Views

Author

Eric Angelini and Jean-Marc Falcoz, Oct 11 2016

Keywords

Comments

The sequence starts with a(1) = 1 and is always extended with the smallest integer not yet present that does not lead to a contradiction.
From Michael De Vlieger, Oct 12 2016 (Start):
Each nonprime c = A018252(n) followed by c primes starting with prime(A175967(n)).
The position of nonprimes in a(n) is {1, 3, 8, 15, 24, 34, 45, 58, 73, 89, 106, 125, ...}. (End)

Examples

			As a(1) = 1, we take for a(2) the prime "2"; we then extend the sequence with a(3) which must be the smallest nonprime not yet present: this is "4"; we take for a(4), a(5), a(6) and a(7) the 4 smallest primes not yet present: they are 3, 5, 7 and 11; we then extend the sequence with the smallest nonprime available, which is a(8) = 6. Etc.
		

Crossrefs

Cf. A018252 (nonprimes), A175967.

Programs

  • Mathematica
    c = Select[Range@ 120, ! PrimeQ@ # &]; Table[Prepend[Prime@ Most[Range @@ Take[FoldList[Plus, 0, Take[c, n]] + 1, -2]], c[[n]]], {n, 9}] // Flatten (* Michael De Vlieger, Oct 12 2016 *)
Showing 1-8 of 8 results.