The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A303918 Prime numbers with property that left half and right half have the same pattern of consecutive increasing/decreasing/equal digits:. 0
 1021, 1031, 1051, 1061, 1063, 1087, 1091, 1093, 1097, 1201, 1213, 1217, 1223, 1229, 1237, 1249, 1259, 1279, 1289, 1301, 1303, 1307, 1319, 1327, 1367, 1409, 1423, 1427, 1429, 1439, 1447, 1459, 1489, 1523, 1549, 1559, 1567, 1579, 1601, 1607, 1609, 1613, 1619, 1627, 1637, 1657, 1667, 1669, 1709, 1723, 1747 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Each term in the sequence must have an even number of digits to allow comparison of its two halves. Minimum four-digit term is 1021, maximum is 9887; minimum six-digit term is 100411, maximum is 998551. LINKS Table of n, a(n) for n=1..51. EXAMPLE 1021 belongs to the sequence as it is prime and the consecutive digits in its left and right halves (10 and 21, respectively) have the same pattern: 1 > 0, 2 > 1. The prime number 100411 belongs to the sequence as the consecutive digits in its left half (100) and right half (411) have the same pattern: 1 > 0 = 0, 4 > 1 = 1. MATHEMATICA pt[w_] := Sign@ Differences@ w; ok[p_] := PrimeQ[p] && Block[{d = IntegerDigits[p], m}, m = Length[d]; EvenQ[m] && pt@ Take[d, m/2] == pt@ Take[d, -m/2]]; Select[ Range[1000, 1747], ok] (* Giovanni Resta, May 04 2018 *) PROG (Python) #program to get all terms less than one million def pattern(p): l=len(p) s="" for k in range(l-1): if p[k+1]>p[k]: s=s+"+" elif p[k+1]

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 21 04:06 EDT 2024. Contains 372720 sequences. (Running on oeis4.)