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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A067379 Primes expressible as the sum of (at least two) consecutive primes in at least 3 ways.

Original entry on oeis.org

311, 863, 1151, 1367, 1951, 2393, 2647, 2689, 3389, 4957, 5059, 5153, 7451, 7901, 8819, 10499, 10859, 10949, 12329, 12641, 12713, 13127, 13297, 14369, 14699, 14759, 14951, 15091, 15329, 15527, 16223, 16249, 16829, 18089, 18311, 18401
Offset: 1

Views

Author

Patrick De Geest, Feb 04 2002

Keywords

Crossrefs

Programs

  • Mathematica
    m=2*6!; lst={}; Do[p=Prime[a]; Do[p+=Prime[b]; If[PrimeQ[p]&&pVladimir Joseph Stephan Orlovsky, Aug 15 2009 *)

Formula

Prime(n) such that A307610(n) > 3. - Ray Chandler, Sep 21 2023

A084146 Integers that have exactly one representation as a sum of two or more consecutive primes.

Original entry on oeis.org

5, 8, 10, 12, 15, 17, 18, 23, 24, 26, 28, 30, 31, 39, 42, 48, 49, 52, 53, 56, 58, 59, 67, 68, 71, 75, 77, 78, 84, 88, 95, 97, 98, 101, 102, 109, 121, 124, 127, 128, 129, 131, 132, 139, 144, 150, 155, 156, 158, 159, 160, 161, 162, 168, 169, 172, 173, 181, 184, 186, 192
Offset: 1

Views

Author

Eric W. Weisstein, May 15 2003

Keywords

Comments

More fundamental than A050936, which gives integers having 1 *or more* such representations

Crossrefs

Cf. A050936, A084143, A337095 (subset of primes).

Programs

  • Maple
    # uses code of A084143
    isA084146 := proc(n::integer)
        if A084143(n) = 1 then
            true;
        else
            false;
        end if;
    end proc:
    for n from 1 to 300 do
        if isA084146(n) then
            printf("%d,",n) ;
        end if;
    end do: # R. J. Mathar, Aug 19 2020

Formula

A084143(a(n)) = 1. - Ray Chandler, Sep 20 2023

Extensions

More terms from Matthew Conroy, May 25 2003

A067373 Integers expressible as the sum of (at least two) consecutive primes in at least 3 ways.

Original entry on oeis.org

240, 287, 311, 340, 371, 510, 660, 803, 863, 864, 931, 961, 990, 1012, 1060, 1099, 1104, 1151, 1164, 1236, 1313, 1320, 1367, 1392, 1524, 1643, 1650, 1710, 1788, 1793, 1854, 1951, 1956, 2040, 2303, 2304, 2387, 2393, 2436, 2507, 2556, 2586, 2647, 2670
Offset: 1

Views

Author

Patrick De Geest, Feb 04 2002

Keywords

Examples

			240 = (113 + 127) = (53 + 59 + 61 + 67) = (17 + 19 + 23 + 29 + 31 + 37 + 41 + 43) or (#2,113) (#4,53) (#8,17).
		

Crossrefs

Programs

  • Mathematica
    m=3*5!; lst={}; Do[p=Prime[a]; Do[p+=Prime[b]; If[pVladimir Joseph Stephan Orlovsky, Aug 15 2009 *)

Formula

A084143(a(n)) > 2. - Ray Chandler, Sep 20 2023

Extensions

Offset corrected by Donovan Johnson, Nov 14 2013

A067374 Integers expressible as the sum of (at least two) consecutive primes in at least 4 ways.

Original entry on oeis.org

311, 863, 1164, 1320, 1650, 1854, 2856, 2867, 3198, 3264, 3754, 4200, 4920, 5100, 5770, 5999, 6504, 8152, 10134, 10320, 10536, 10649, 11058, 12294, 12438, 12762, 12820, 12954, 12990, 14369, 14699, 14826, 15329, 15610, 15762, 16199, 16277
Offset: 1

Views

Author

Patrick De Geest, Feb 04 2002

Keywords

Examples

			E.g., 311 = 101 + 103 + 107 = 53 + 59 + 61 + 67 + 71 = 31 + 37 + 41 + 43 + 47 + 53 + 59 = 11 + 13 + 17 + 19 + 23 + 29 + 31 + 37 + 41 + 43 + 47.
		

Crossrefs

Programs

  • Mathematica
    Clear[lst,lst1,m,n,p,a,b] m=2*6!; lst={}; Do[p=Prime[a]; Do[p+=Prime[b]; If[pVladimir Joseph Stephan Orlovsky, Aug 15 2009 *)

Formula

A084143(a(n)) > 3. - Ray Chandler, Sep 20 2023

Extensions

Offset corrected by Donovan Johnson, Nov 14 2013

A067375 Integers expressible as the sum of (at least two) consecutive primes in at least 5 ways.

Original entry on oeis.org

16277, 20272, 25416, 28500, 34421, 41074, 45101, 46660, 50560, 53424, 59068, 68787, 70104, 70692, 71548, 78756, 85433, 85481, 88453, 94350, 98881, 105827, 117907, 120151, 121847, 125952, 130638, 130789, 131420, 132539, 133367, 134376, 135918, 139853, 158810
Offset: 1

Views

Author

Patrick De Geest, Feb 04 2002

Keywords

Examples

			E.g. 16277 = (#7,2297) (#11,1451) (#13,1213) (#35,359) (#37,331).
		

Crossrefs

Programs

  • Mathematica
    t={};Do[p=Prime[m];Do[p=p+Prime[n];If[p<200000,AppendTo[t,p]],{n,m+1,7001}],{m,1,7000}];t=Sort@t;f5[l_]:=Module[{t={}},Do[If[l[[n]]==l[[n+4]],AppendTo[t,l[[n]]]],{n,Length[l]-4}];t];Union@f5[t] (* Vladimir Joseph Stephan Orlovsky, Jan 30 2012 *)

Formula

A084143(a(n)) > 4. - Ray Chandler, Sep 20 2023

Extensions

Offset and a(35) corrected by Donovan Johnson, Nov 14 2013

A087072 Numbers having no partitions into a sum of two or more consecutive primes.

Original entry on oeis.org

1, 2, 3, 4, 6, 7, 9, 11, 13, 14, 16, 19, 20, 21, 22, 25, 27, 29, 32, 33, 34, 35, 37, 38, 40, 43, 44, 45, 46, 47, 50, 51, 54, 55, 57, 61, 62, 63, 64, 65, 66, 69, 70, 73, 74, 76, 79, 80, 81, 82, 85, 86, 87, 89, 91, 92, 93, 94, 96, 99, 103, 104, 105, 106, 107, 108, 110, 111
Offset: 1

Views

Author

Reinhard Zumkeller, Aug 08 2003

Keywords

Comments

A084143(a(n)) = 0; complement of A050936.

Crossrefs

A367021 Numbers that can be written as both the sum of two or more consecutive nonprimes and the sum of two or more consecutive primes.

Original entry on oeis.org

5, 10, 17, 18, 23, 26, 28, 31, 36, 39, 41, 49, 53, 58, 59, 60, 67, 68, 71, 75, 77, 78, 83, 84, 90, 95, 97, 101, 102, 109, 112, 121, 124, 127, 128, 129, 131, 132, 138, 139, 143, 150, 152, 155, 156, 158, 159, 160, 161, 162, 168, 169, 172, 173, 180, 181, 184, 187, 192
Offset: 1

Views

Author

Tamas Sandor Nagy, Nov 01 2023

Keywords

Comments

It seems that more than one consecutive number set from one kind or the other may exist for a term. Also, for some terms, an equal number of addends from each kind may correspond.

Examples

			5 is a term because 5 = 1 + 4 = 2 + 3, which is the sum of two consecutive nonprimes and also the sum of two consecutive primes.
17 is a term because 17 = 8 + 9 = 2 + 3 + 5 + 7, the sum of two consecutive nonprimes and also the sum of four consecutive primes.
		

Crossrefs

Programs

  • Python
    from sympy import isprime
    primes = [x for x in range(2,3000) if isprime(x)]
    comps = [x for x in range(1,3000) if not isprime(x)]
    psums = set(sum(primes[p:p+pn]) for pn in range(2,100) for p in range(len(primes)-pn))
    csums = set(sum(comps[c:c+cn]) for cn in range(2,100) for c in range(len(comps)-cn))
    terms = sorted(list(psums.intersection(csums)))
    print(terms)
    # David Consiglio, Jr., Dec 18 2023

Extensions

More terms from David Consiglio, Jr., Dec 18 2023

A067376 Smallest integer expressible as the sum of (at least two) consecutive primes in n ways.

Original entry on oeis.org

5, 36, 240, 311, 16277, 130638, 218918, 9186778, 274452156, 4611108324, 12941709050
Offset: 1

Views

Author

Patrick De Geest, Feb 04 2002

Keywords

Comments

a(10)-a(11) found by Wilfred Whiteside in 2007 (see Rivera link). - Michael S. Branicky, Jul 27 2022

Examples

			In n=7 ways: 218918 = (#12,18199) (#16,13619) (#22,9851) (#28,7691) (#38,5623) (#46,4561) (#62,3301).
		

Crossrefs

Extensions

Offset corrected and a(8)-a(9) from Donovan Johnson, Mar 14 2010
a(10) confirmed and a(10)-a(11) entered by Michael S. Branicky, Jul 27 2022

A135363 Sums of two or more consecutive semiprimes.

Original entry on oeis.org

10, 15, 19, 24, 25, 29, 33, 36, 39, 43, 47, 48, 50, 51, 54, 58, 59, 60, 67, 68, 69, 72, 73, 75, 77, 79, 82, 83, 84, 85, 91, 93, 94, 95, 97, 100, 101, 102, 106, 107, 109, 112, 115, 116, 118, 120, 122, 123, 126, 127, 128, 133, 134, 140, 142, 143, 146, 148, 151, 152
Offset: 1

Views

Author

Jonathan Vos Post, Dec 09 2007

Keywords

Comments

This is to A050936 as A001358 is to A000040.

Examples

			a(1) = 10 = 4 + 6.
a(2) = 15 = 6 + 9.
a(3) = 19 = 9 + 10 = 4 + 6 + 9.
a(4) = 24 = 10 + 14.
a(5) = 25 = 6 + 9 + 10.
a(6) = 29 = 14 + 15 = 4 + 6 + 9 + 10.
a(7) = 33 = 9 + 10 + 14.
a(8) = 36 = 15 + 21.
a(9) = 39 = 10 + 14 + 15.
a(10) = 43 = 21 + 22.
		

Crossrefs

Programs

  • Maple
    isA001358 := proc(n) if numtheory[bigomega](n) = 2 then true; else false ; fi ; end: A001358 := proc(n) option remember ; local a; if n <= 3 then op(n,[4,6,9]) ; else a := A001358(n-1)+1 ; while not isA001358(a) do a := a+1 ; od ; RETURN(a) ; fi ; end: isA135363 := proc(n) local frst,lst, psum ; for frst from 1 do if A001358(frst) >= n then RETURN(false) ; fi ; for lst from frst+1 do psum := add(A001358(k),k=frst..lst) ; if psum = n then RETURN(true) ; elif psum > n then break ; fi ; od: od: end: for n from 4 to 200 do if isA135363(n) then printf("%d, ",n) ; fi ; od: # R. J. Mathar, Dec 11 2007
  • Mathematica
    okQ[n_] := With[{SP = Select[Range[n], PrimeOmega[#] == 2 &]}, Select[IntegerPartitions[n, {2, Infinity}, SP], SequencePosition[SP, Reverse@#] != {}&]] != {};
    Reap[For[k = 10, k < 200, k++, If[okQ[k], Print[k]; Sow[k]]]][[2, 1]] (* Jean-François Alcover, Jan 29 2024 *)

Extensions

Corrected and extended by R. J. Mathar, Dec 11 2007

A163246 Squares which can be represented as the sum of consecutive primes in more than one way.

Original entry on oeis.org

36, 100, 576, 841, 961, 1764, 1849, 2209, 2304, 7056, 22801, 24649, 25600, 30276, 31684, 32400, 36481, 39601, 40000, 47524, 48400, 48841, 57600, 58081, 66564, 69169, 69696, 76729, 77284, 80089, 85849, 93636, 94864, 96721, 112896, 119716, 128164, 134689, 138384, 140625, 142884, 147456
Offset: 1

Views

Author

Gaurav Kumar, Jul 23 2009

Keywords

Examples

			6^2 = 36 = 5 + 7 + 11 + 13 = 17 + 19.
		

Crossrefs

Formula

{ A000290 } intersect { A034707 }.
{ A000290 } intersect { A050936 }.
k^2 such that A084143(k^2) > 1. - Georg Fischer, Jul 08 2022

Extensions

Offset corrected by Arkadiusz Wesolowski, Mar 28 2012
Duplicate 2304 removed and some missing terms inserted by Georg Fischer, Jul 08 2022
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