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!)
 A098767 Deficient numbers whose reversal is also a deficient number. 2
 1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 19, 22, 23, 25, 26, 29, 31, 32, 33, 34, 35, 37, 38, 39, 41, 43, 44, 46, 47, 49, 50, 51, 52, 53, 55, 57, 58, 59, 61, 62, 64, 67, 68, 71, 73, 74, 75, 76, 77, 79, 83, 85, 86, 89, 91, 92, 93, 94, 95, 97, 98, 99, 101, 103, 105, 106 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Ivan Neretin, Table of n, a(n) for n = 1..10000 EXAMPLE a(12)=14 because 14 and reverse of 14, i.e., 41, are deficient numbers. a(13)=15 because 15 is a deficient number which on reversing its digits also gives a deficient number, i.e., 51. MATHEMATICA Select[Range@106, DivisorSigma[1, #] < 2 # && DivisorSigma[1, n = FromDigits@Reverse@IntegerDigits@#] < 2 n &] (* Ivan Neretin, Dec 19 2015 *) PROG (PARI) isdefic(n) = (sigma(n) < 2*n); isok(n) = isdefic(n) && isdefic(eval(concat(Vecrev(Str(n))))); \\ Michel Marcus, Dec 20 2015 CROSSREFS Cf. A005100. Sequence in context: A051772 A049093 A098901 * A333559 A153381 A307750 Adjacent sequences:  A098764 A098765 A098766 * A098768 A098769 A098770 KEYWORD easy,nonn,base AUTHOR Shyam Sunder Gupta, Oct 02 2004 EXTENSIONS Edited by N. J. A. Sloane at the suggestion of Andrew S. Plewe, Jun 11 2007 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 October 1 15:05 EDT 2020. Contains 337443 sequences. (Running on oeis4.)