The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A335732 Emirps whose concatenation of adjacent digit differences either form an emirp that also has this characteristic or form a single digit prime, and whose emirp also has this characteristic. 0
 13, 31, 79, 97, 347, 709, 743, 769, 907, 967, 1847, 7481 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS EXAMPLE 7481 is in the list as the concatenation of adjacent digit differences forms an emirp (i.e., |7-4|=3; |4-8|=4; |8-1|=7; which form 347, which is an emirp as 743 is also prime). Furthermore, for 347, |3-4|=1; |4-7|=3; forms 13, which is an emirp as 31 is also prime. Finally, |1-3| = 2, which is prime. This characteristic is also true for the emirp of 7481 which is 1847 (i.e., 1847 forms 743 which forms 31 which finally forms 2). PROG (Python) from sympy.ntheory import isprime as isp i = [] for a in range(10, 1000000):     if isp(a):         b = str(a)         d=[]         for c in range(0, len(b)-1):             ee = abs(int(b[c])-int(b[c+1]))             d.append(str(ee))         f = ''.join(d)         g = b[::-1]         if isp(int(f)) and isp(int(g)):             if len(b)<3:                 i.append(b)             else:                 if f in i:                     i.append(b) print(', '.join(i)) CROSSREFS A subset of A006567. Sequence in context: A158723 A211116 A107288 * A342706 A095379 A160772 Adjacent sequences:  A335729 A335730 A335731 * A335733 A335734 A335735 KEYWORD base,nonn,fini,full,less AUTHOR Ray G. Opao, Jun 20 2020 STATUS approved

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

Last modified June 15 12:29 EDT 2021. Contains 345048 sequences. (Running on oeis4.)