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.

A161190 Sums of prime points found in four grids in each corner of a square.

Original entry on oeis.org

281, 414, 857, 942, 1124, 2569, 1295, 1433, 1094, 2426, 2730, 3000, 2459, 2575, 1818, 4991, 5331, 3363, 1163, 5006, 5226, 1381, 7213, 7493, 4729, 8217, 3456, 3546, 3684, 5615, 7834, 8090, 6243, 2143, 8862, 11407, 9396, 12019, 4906, 7631, 2591, 13411
Offset: 1

Views

Author

Enoch Haga, Jun 06 2009, Jun 24 2009, Jun 27 2009

Keywords

Comments

When the points are marked on drawn lines the concavity is apparent.
The lines are indicated with capital letters A through G (see Fig. 6 in Link)
- A
B 1 7 12 16 19 21
C 2 8 13 17 20
D 3 9 14 18
E 4 10 15
F 5 11
G 6
Reading diagonally across the bottom of the first of 4 diagonals:
6,11,15,18,20,21. The next 3 diagonals are formed by adding 1 to 21, e.g.,
22,27,31,34,36,37
38,43,47,50,52,53
54,59,63,66,68,69. This grid is numbered 1, and the next, 2, starts at 70.
Each numbered set of 4 grids fills the corners of a square delineating and surrounding a circle suggested by the 24 numbers above on its circumference.

Examples

			a(1)=281 because that is the sum of the prime points in the first set of 4 lower diagonals in the first 4 corner grids: (11+31+37+43+47+53+59=281).

Links

Crossrefs

Cf. A161191, A161192, A161193, A161194.

Programs

  • UBASIC
    10 'rotate points, Enoch Haga, Jun 05 2009
20 F=5
30 A=F+1:print A;:if A=prmdiv(A) then S=S+B:print "*";
40 B=A+5:print B;:if B=prmdiv(B) then S=S+B:print "*";
50 C=B+4:print C;:if C=prmdiv(C) then S=S+C:print "*";
60 D=C+3:print D;:if D=prmdiv(D) then S=S+D:print "*";
70 E=D+2:print E;:if E=prmdiv(E) then S=S+E:print "*";
80 F=E+1:print F;:if F=prmdiv(F) then S=S+F:print "*";
90 R=R+1:if R=4 and S=prmdiv(S) then print S;"*";
100 if R=4 then print R;S;:T=T+1:print T:R=0:S=0
110 stop:goto 30

Extensions

Partially edited by Jon E. Schoenfield, Feb 26 2013

A161194 Index of last term where no prime sums occur in A161190 in a 4 diagonal set of 24 terms.

Original entry on oeis.org

88, 116, 149, 178, 207, 220, 258, 259, 307, 322, 326, 343, 344, 367, 380, 427, 498, 533, 550, 557, 558, 564, 628, 638, 652, 718, 742, 743, 751, 767, 795, 818, 860, 863, 891, 999, 1000, 1008, 1009, 1028, 1034, 1078, 1088, 1094, 1111, 1138, 1199, 1230, 1234
Offset: 1

Views

Author

Enoch Haga, Jun 06 2009

Keywords

Comments

This sequence comprises the indices for A161193.

Examples

			a(1)=88 because that is the index of the first set of 24 terms in 4 diagonals where none is prime.

Crossrefs

Cf. A161190, A161191, A161192, A161193.

Programs

Formula

These are the indices for the sets of 4 diagonals (comprising the 24 points on the circumference of a circle) where no primes occur.

A161192 Consecutive pairs of prime point sums in A161191 (includes triples).

Original entry on oeis.org

1381, 7213, 2591, 13411, 8783, 2971, 9733, 9931, 4831, 4933, 5903, 6011, 30259, 20879, 35059, 25321, 8501, 10223, 30841, 10559, 31817, 11173, 11243, 36767, 12347, 13567, 13627, 41039, 14251, 42937, 17099, 51539, 17231, 18443, 55579, 18587
Offset: 1

Views

Author

Enoch Haga, Jun 06 2009

Keywords

Comments

This sequence is a subsequence of A161191.

Examples

			a(1) and a(2) above, 1381 and 7213, are A161191(6) and A161191(7).

Crossrefs

Cf. A161190, A161191, A161193, A161194.

Programs

Formula

Select pairs (including triples) of prime point sums in A161191.
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement.